babel-types

What is babel-types?

The babel-types package is a part of the Babel compiler ecosystem. It provides builders, validators, and conversion utilities for the various types of nodes in the Abstract Syntax Tree (AST) used by Babel. This package is essential for manipulating the AST generated or consumed by Babel, allowing for custom transformations and analysis of JavaScript code.

What are babel-types's main functionalities?

AST Node Builders

Builders are functions that help in creating AST nodes. This example demonstrates creating a binary expression node that represents the multiplication of two identifiers, 'a' and 'b'.

const t = require('babel-types');
const binaryExpression = t.binaryExpression('*', t.identifier('a'), t.identifier('b'));

AST Node Validators

Validators are functions that check if a node is of a certain type or meets certain criteria. In this example, the validator checks if the node is an identifier with the name 'a'.

const t = require('babel-types');
const isValid = t.isIdentifier(t.identifier('a'), { name: 'a' });

Type Conversion Utilities

Conversion utilities allow for the transformation of one type of node into another. This example shows converting a numeric literal into a string literal.

const t = require('babel-types');
const numericLiteral = t.numericLiteral(5);
const asStringLiteral = t.stringLiteral(`${numericLiteral.value}`);

Other packages similar to babel-types

@babel/types

This is the newer version of babel-types, rebranded and scoped under the Babel organization. It offers the same functionalities but is more actively maintained and includes updates for the latest JavaScript features.

recast

Recast provides AST manipulation capabilities with a focus on preserving the original formatting as much as possible. While babel-types is more about creating and validating AST nodes, recast is geared towards parsing and reprinting code with minimal changes.

acorn

Acorn is a fast, small JavaScript parser that generates an AST. While it doesn't offer manipulation utilities like babel-types, it's often used in conjunction with other tools for analysis and transformation tasks.

README

babel-types

This module contains methods for building ASTs manually and for checking the types of AST nodes.

Install

npm install --save-dev babel-types

API

anyTypeAnnotation

t.anyTypeAnnotation()

See also t.isAnyTypeAnnotation(node, opts) and t.assertAnyTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

arrayExpression

t.arrayExpression(elements)

See also t.isArrayExpression(node, opts) and t.assertArrayExpression(node, opts).

Aliases: Expression

• elements: Array<null | Expression | SpreadElement> (default: [])

---

arrayPattern

t.arrayPattern(elements, typeAnnotation)

See also t.isArrayPattern(node, opts) and t.assertArrayPattern(node, opts).

Aliases: Pattern, LVal

• elements: Array<Identifier | Pattern | RestElement> (required)
• typeAnnotation (required)
• decorators: Array<Decorator> (default: null)

---

arrayTypeAnnotation

t.arrayTypeAnnotation(elementType)

See also t.isArrayTypeAnnotation(node, opts) and t.assertArrayTypeAnnotation(node, opts).

Aliases: Flow

• elementType (required)

---

arrowFunctionExpression

t.arrowFunctionExpression(params, body, async)

See also t.isArrowFunctionExpression(node, opts) and t.assertArrowFunctionExpression(node, opts).

Aliases: Scopable, Function, BlockParent, FunctionParent, Expression, Pureish

• params: Array<LVal> (required)
• body: BlockStatement | Expression (required)
• async: boolean (default: false)
• returnType (default: null)
• typeParameters (default: null)

---

assignmentExpression

t.assignmentExpression(operator, left, right)

See also t.isAssignmentExpression(node, opts) and t.assertAssignmentExpression(node, opts).

Aliases: Expression

• operator: string (required)
• left: LVal (required)
• right: Expression (required)

---

assignmentPattern

t.assignmentPattern(left, right)

See also t.isAssignmentPattern(node, opts) and t.assertAssignmentPattern(node, opts).

Aliases: Pattern, LVal

• left: Identifier (required)
• right: Expression (required)
• decorators: Array<Decorator> (default: null)

---

awaitExpression

t.awaitExpression(argument)

See also t.isAwaitExpression(node, opts) and t.assertAwaitExpression(node, opts).

Aliases: Expression, Terminatorless

• argument: Expression (required)

---

binaryExpression

t.binaryExpression(operator, left, right)

See also t.isBinaryExpression(node, opts) and t.assertBinaryExpression(node, opts).

Aliases: Binary, Expression

• operator: '+' | '-' | '/' | '%' | '*' | '**' | '&' | '|' | '>>' | '>>>' | '<<' | '^' | '==' | '===' | '!=' | '!==' | 'in' | 'instanceof' | '>' | '<' | '>=' | '<=' (required)
• left: Expression (required)
• right: Expression (required)

---

bindExpression

t.bindExpression(object, callee)

See also t.isBindExpression(node, opts) and t.assertBindExpression(node, opts).

Aliases: Expression

• object (required)
• callee (required)

---

blockStatement

t.blockStatement(body, directives)

See also t.isBlockStatement(node, opts) and t.assertBlockStatement(node, opts).

Aliases: Scopable, BlockParent, Block, Statement

• body: Array<Statement> (required)
• directives: Array<Directive> (default: [])

---

booleanLiteral

t.booleanLiteral(value)

See also t.isBooleanLiteral(node, opts) and t.assertBooleanLiteral(node, opts).

Aliases: Expression, Pureish, Literal, Immutable

• value: boolean (required)

---

booleanLiteralTypeAnnotation

t.booleanLiteralTypeAnnotation()

See also t.isBooleanLiteralTypeAnnotation(node, opts) and t.assertBooleanLiteralTypeAnnotation(node, opts).

Aliases: Flow

---

booleanTypeAnnotation

t.booleanTypeAnnotation()

See also t.isBooleanTypeAnnotation(node, opts) and t.assertBooleanTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

breakStatement

t.breakStatement(label)

See also t.isBreakStatement(node, opts) and t.assertBreakStatement(node, opts).

Aliases: Statement, Terminatorless, CompletionStatement

• label: Identifier (default: null)

---

callExpression

t.callExpression(callee, arguments)

See also t.isCallExpression(node, opts) and t.assertCallExpression(node, opts).

Aliases: Expression

• callee: Expression (required)
• arguments: Array<Expression | SpreadElement> (required)

---

catchClause

t.catchClause(param, body)

See also t.isCatchClause(node, opts) and t.assertCatchClause(node, opts).

Aliases: Scopable

• param: Identifier (required)
• body: BlockStatement (required)

---

classBody

t.classBody(body)

See also t.isClassBody(node, opts) and t.assertClassBody(node, opts).

• body: Array<ClassMethod | ClassProperty> (required)

---

classDeclaration

t.classDeclaration(id, superClass, body, decorators)

See also t.isClassDeclaration(node, opts) and t.assertClassDeclaration(node, opts).

Aliases: Scopable, Class, Statement, Declaration, Pureish

• id: Identifier (required)
• superClass: Expression (default: null)
• body: ClassBody (required)
• decorators: Array<Decorator> (required)
• implements (default: null)
• mixins (default: null)
• superTypeParameters (default: null)
• typeParameters (default: null)

---

classExpression

t.classExpression(id, superClass, body, decorators)

See also t.isClassExpression(node, opts) and t.assertClassExpression(node, opts).

Aliases: Scopable, Class, Expression, Pureish

• id: Identifier (default: null)
• superClass: Expression (default: null)
• body: ClassBody (required)
• decorators: Array<Decorator> (required)
• implements (default: null)
• mixins (default: null)
• superTypeParameters (default: null)
• typeParameters (default: null)

---

classImplements

t.classImplements(id, typeParameters)

See also t.isClassImplements(node, opts) and t.assertClassImplements(node, opts).

Aliases: Flow

• id (required)
• typeParameters (required)

---

classMethod

t.classMethod(kind, key, params, body, computed, static)

See also t.isClassMethod(node, opts) and t.assertClassMethod(node, opts).

Aliases: Function, Scopable, BlockParent, FunctionParent, Method

• kind: "get" | "set" | "method" | "constructor" (default: 'method')
• keyif computed then Expression else Identifier | Literal (required)
• params: Array<LVal> (required)
• body: BlockStatement (required)
• computed: boolean (default: false)
• static: boolean (default: false)
• async: boolean (default: false)
• decorators (default: null)
• generator: boolean (default: false)
• returnType (default: null)
• typeParameters (default: null)

---

classProperty

t.classProperty(key, value, typeAnnotation, decorators, computed)

See also t.isClassProperty(node, opts) and t.assertClassProperty(node, opts).

Aliases: Property

• key (required)
• value (required)
• typeAnnotation (required)
• decorators (required)
• computed: boolean (default: false)

---

conditionalExpression

t.conditionalExpression(test, consequent, alternate)

See also t.isConditionalExpression(node, opts) and t.assertConditionalExpression(node, opts).

Aliases: Expression, Conditional

• test: Expression (required)
• consequent: Expression (required)
• alternate: Expression (required)

---

continueStatement

t.continueStatement(label)

See also t.isContinueStatement(node, opts) and t.assertContinueStatement(node, opts).

Aliases: Statement, Terminatorless, CompletionStatement

• label: Identifier (default: null)

---

debuggerStatement

t.debuggerStatement()

See also t.isDebuggerStatement(node, opts) and t.assertDebuggerStatement(node, opts).

Aliases: Statement

---

declareClass

t.declareClass(id, typeParameters, extends, body)

See also t.isDeclareClass(node, opts) and t.assertDeclareClass(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• extends (required)
• body (required)

---

declareExportDeclaration

t.declareExportDeclaration(declaration, specifiers, source)

See also t.isDeclareExportDeclaration(node, opts) and t.assertDeclareExportDeclaration(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• declaration (required)
• specifiers (required)
• source (required)

---

declareFunction

t.declareFunction(id)

See also t.isDeclareFunction(node, opts) and t.assertDeclareFunction(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)

---

declareInterface

t.declareInterface(id, typeParameters, extends, body)

See also t.isDeclareInterface(node, opts) and t.assertDeclareInterface(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• extends (required)
• body (required)

---

declareModule

t.declareModule(id, body)

See also t.isDeclareModule(node, opts) and t.assertDeclareModule(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• body (required)

---

declareModuleExports

t.declareModuleExports(typeAnnotation)

See also t.isDeclareModuleExports(node, opts) and t.assertDeclareModuleExports(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• typeAnnotation (required)

---

declareOpaqueType

t.declareOpaqueType(id, typeParameters, supertype)

See also t.isDeclareOpaqueType(node, opts) and t.assertDeclareOpaqueType(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• supertype (required)

---

declareTypeAlias

t.declareTypeAlias(id, typeParameters, right)

See also t.isDeclareTypeAlias(node, opts) and t.assertDeclareTypeAlias(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• right (required)

---

declareVariable

t.declareVariable(id)

See also t.isDeclareVariable(node, opts) and t.assertDeclareVariable(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)

---

decorator

t.decorator(expression)

See also t.isDecorator(node, opts) and t.assertDecorator(node, opts).

• expression: Expression (required)

---

directive

t.directive(value)

See also t.isDirective(node, opts) and t.assertDirective(node, opts).

• value: DirectiveLiteral (required)

---

directiveLiteral

t.directiveLiteral(value)

See also t.isDirectiveLiteral(node, opts) and t.assertDirectiveLiteral(node, opts).

• value: string (required)

---

doExpression

t.doExpression(body)

See also t.isDoExpression(node, opts) and t.assertDoExpression(node, opts).

Aliases: Expression

• body: BlockStatement (required)

---

doWhileStatement

t.doWhileStatement(test, body)

See also t.isDoWhileStatement(node, opts) and t.assertDoWhileStatement(node, opts).

Aliases: Statement, BlockParent, Loop, While, Scopable

• test: Expression (required)
• body: Statement (required)

---

emptyStatement

t.emptyStatement()

See also t.isEmptyStatement(node, opts) and t.assertEmptyStatement(node, opts).

Aliases: Statement

---

emptyTypeAnnotation

t.emptyTypeAnnotation()

See also t.isEmptyTypeAnnotation(node, opts) and t.assertEmptyTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

existentialTypeParam

t.existentialTypeParam()

See also t.isExistentialTypeParam(node, opts) and t.assertExistentialTypeParam(node, opts).

Aliases: Flow

---

exportAllDeclaration

t.exportAllDeclaration(source)

See also t.isExportAllDeclaration(node, opts) and t.assertExportAllDeclaration(node, opts).

Aliases: Statement, Declaration, ModuleDeclaration, ExportDeclaration

• source: StringLiteral (required)

---

exportDefaultDeclaration

t.exportDefaultDeclaration(declaration)

See also t.isExportDefaultDeclaration(node, opts) and t.assertExportDefaultDeclaration(node, opts).

Aliases: Statement, Declaration, ModuleDeclaration, ExportDeclaration

• declaration: FunctionDeclaration | ClassDeclaration | Expression (required)

---

exportDefaultSpecifier

t.exportDefaultSpecifier(exported)

See also t.isExportDefaultSpecifier(node, opts) and t.assertExportDefaultSpecifier(node, opts).

Aliases: ModuleSpecifier

• exported: Identifier (required)

---

exportNamedDeclaration

t.exportNamedDeclaration(declaration, specifiers, source)

See also t.isExportNamedDeclaration(node, opts) and t.assertExportNamedDeclaration(node, opts).

Aliases: Statement, Declaration, ModuleDeclaration, ExportDeclaration

• declaration: Declaration (default: null)
• specifiers: Array<ExportSpecifier> (required)
• source: StringLiteral (default: null)

---

exportNamespaceSpecifier

t.exportNamespaceSpecifier(exported)

See also t.isExportNamespaceSpecifier(node, opts) and t.assertExportNamespaceSpecifier(node, opts).

Aliases: ModuleSpecifier

• exported: Identifier (required)

---

exportSpecifier

t.exportSpecifier(local, exported)

See also t.isExportSpecifier(node, opts) and t.assertExportSpecifier(node, opts).

Aliases: ModuleSpecifier

• local: Identifier (required)
• exported: Identifier (required)

---

expressionStatement

t.expressionStatement(expression)

See also t.isExpressionStatement(node, opts) and t.assertExpressionStatement(node, opts).

Aliases: Statement, ExpressionWrapper

• expression: Expression (required)

---

file

t.file(program, comments, tokens)

See also t.isFile(node, opts) and t.assertFile(node, opts).

• program: Program (required)
• comments (required)
• tokens (required)

---

forAwaitStatement

t.forAwaitStatement(left, right, body)

See also t.isForAwaitStatement(node, opts) and t.assertForAwaitStatement(node, opts).

Aliases: Scopable, Statement, For, BlockParent, Loop, ForXStatement

• left: VariableDeclaration | LVal (required)
• right: Expression (required)
• body: Statement (required)

---

forInStatement

t.forInStatement(left, right, body)

See also t.isForInStatement(node, opts) and t.assertForInStatement(node, opts).

Aliases: Scopable, Statement, For, BlockParent, Loop, ForXStatement

• left: VariableDeclaration | LVal (required)
• right: Expression (required)
• body: Statement (required)

---

forOfStatement

t.forOfStatement(left, right, body)

See also t.isForOfStatement(node, opts) and t.assertForOfStatement(node, opts).

Aliases: Scopable, Statement, For, BlockParent, Loop, ForXStatement

• left: VariableDeclaration | LVal (required)
• right: Expression (required)
• body: Statement (required)

---

forStatement

t.forStatement(init, test, update, body)

See also t.isForStatement(node, opts) and t.assertForStatement(node, opts).

Aliases: Scopable, Statement, For, BlockParent, Loop

• init: VariableDeclaration | Expression (default: null)
• test: Expression (default: null)
• update: Expression (default: null)
• body: Statement (required)

---

functionDeclaration

t.functionDeclaration(id, params, body, generator, async)

See also t.isFunctionDeclaration(node, opts) and t.assertFunctionDeclaration(node, opts).

Aliases: Scopable, Function, BlockParent, FunctionParent, Statement, Pureish, Declaration

• id: Identifier (required)
• params: Array<LVal> (required)
• body: BlockStatement (required)
• generator: boolean (default: false)
• async: boolean (default: false)
• returnType (default: null)
• typeParameters (default: null)

---

functionExpression

t.functionExpression(id, params, body, generator, async)

See also t.isFunctionExpression(node, opts) and t.assertFunctionExpression(node, opts).

Aliases: Scopable, Function, BlockParent, FunctionParent, Expression, Pureish

• id: Identifier (default: null)
• params: Array<LVal> (required)
• body: BlockStatement (required)
• generator: boolean (default: false)
• async: boolean (default: false)
• returnType (default: null)
• typeParameters (default: null)

---

functionTypeAnnotation

t.functionTypeAnnotation(typeParameters, params, rest, returnType)

See also t.isFunctionTypeAnnotation(node, opts) and t.assertFunctionTypeAnnotation(node, opts).

Aliases: Flow

• typeParameters (required)
• params (required)
• rest (required)
• returnType (required)

---

functionTypeParam

t.functionTypeParam(name, typeAnnotation)

See also t.isFunctionTypeParam(node, opts) and t.assertFunctionTypeParam(node, opts).

Aliases: Flow

• name (required)
• typeAnnotation (required)

---

genericTypeAnnotation

t.genericTypeAnnotation(id, typeParameters)

See also t.isGenericTypeAnnotation(node, opts) and t.assertGenericTypeAnnotation(node, opts).

Aliases: Flow

• id (required)
• typeParameters (required)

---

identifier

t.identifier(name)

See also t.isIdentifier(node, opts) and t.assertIdentifier(node, opts).

Aliases: Expression, LVal

• name``string (required)
• decorators: Array<Decorator> (default: null)
• typeAnnotation (default: null)

---

ifStatement

t.ifStatement(test, consequent, alternate)

See also t.isIfStatement(node, opts) and t.assertIfStatement(node, opts).

Aliases: Statement, Conditional

• test: Expression (required)
• consequent: Statement (required)
• alternate: Statement (default: null)

---

import

t.import()

See also t.isImport(node, opts) and t.assertImport(node, opts).

Aliases: Expression

---

importDeclaration

t.importDeclaration(specifiers, source)

See also t.isImportDeclaration(node, opts) and t.assertImportDeclaration(node, opts).

Aliases: Statement, Declaration, ModuleDeclaration

• specifiers: Array<ImportSpecifier | ImportDefaultSpecifier | ImportNamespaceSpecifier> (required)
• source: StringLiteral (required)

---

importDefaultSpecifier

t.importDefaultSpecifier(local)

See also t.isImportDefaultSpecifier(node, opts) and t.assertImportDefaultSpecifier(node, opts).

Aliases: ModuleSpecifier

• local: Identifier (required)

---

importNamespaceSpecifier

t.importNamespaceSpecifier(local)

See also t.isImportNamespaceSpecifier(node, opts) and t.assertImportNamespaceSpecifier(node, opts).

Aliases: ModuleSpecifier

• local: Identifier (required)

---

importSpecifier

t.importSpecifier(local, imported)

See also t.isImportSpecifier(node, opts) and t.assertImportSpecifier(node, opts).

Aliases: ModuleSpecifier

• local: Identifier (required)
• imported: Identifier (required)
• importKind: null | 'type' | 'typeof' (default: null)

---

interfaceDeclaration

t.interfaceDeclaration(id, typeParameters, extends, body)

See also t.isInterfaceDeclaration(node, opts) and t.assertInterfaceDeclaration(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• extends (required)
• body (required)

---

interfaceExtends

t.interfaceExtends(id, typeParameters)

See also t.isInterfaceExtends(node, opts) and t.assertInterfaceExtends(node, opts).

Aliases: Flow

• id (required)
• typeParameters (required)

---

intersectionTypeAnnotation

t.intersectionTypeAnnotation(types)

See also t.isIntersectionTypeAnnotation(node, opts) and t.assertIntersectionTypeAnnotation(node, opts).

Aliases: Flow

• types (required)

---

jSXAttribute

t.jSXAttribute(name, value)

See also t.isJSXAttribute(node, opts) and t.assertJSXAttribute(node, opts).

Aliases: JSX, Immutable

• name: JSXIdentifier | JSXNamespacedName (required)
• value: JSXElement | StringLiteral | JSXExpressionContainer (default: null)

---

jSXClosingElement

t.jSXClosingElement(name)

See also t.isJSXClosingElement(node, opts) and t.assertJSXClosingElement(node, opts).

Aliases: JSX, Immutable

• name: JSXIdentifier | JSXMemberExpression (required)

---

jSXElement

t.jSXElement(openingElement, closingElement, children, selfClosing)

See also t.isJSXElement(node, opts) and t.assertJSXElement(node, opts).

Aliases: JSX, Immutable, Expression

• openingElement: JSXOpeningElement (required)
• closingElement: JSXClosingElement (default: null)
• children: Array<JSXText | JSXExpressionContainer | JSXSpreadChild | JSXElement> (required)
• selfClosing (required)

---

jSXEmptyExpression

t.jSXEmptyExpression()

See also t.isJSXEmptyExpression(node, opts) and t.assertJSXEmptyExpression(node, opts).

Aliases: JSX, Expression

---

jSXExpressionContainer

t.jSXExpressionContainer(expression)

See also t.isJSXExpressionContainer(node, opts) and t.assertJSXExpressionContainer(node, opts).

Aliases: JSX, Immutable

• expression: Expression (required)

---

jSXIdentifier

t.jSXIdentifier(name)

See also t.isJSXIdentifier(node, opts) and t.assertJSXIdentifier(node, opts).

Aliases: JSX, Expression

• name: string (required)

---

jSXMemberExpression

t.jSXMemberExpression(object, property)

See also t.isJSXMemberExpression(node, opts) and t.assertJSXMemberExpression(node, opts).

Aliases: JSX, Expression

• object: JSXMemberExpression | JSXIdentifier (required)
• property: JSXIdentifier (required)

---

jSXNamespacedName

t.jSXNamespacedName(namespace, name)

See also t.isJSXNamespacedName(node, opts) and t.assertJSXNamespacedName(node, opts).

Aliases: JSX

• namespace: JSXIdentifier (required)
• name: JSXIdentifier (required)

---

jSXOpeningElement

t.jSXOpeningElement(name, attributes, selfClosing)

See also t.isJSXOpeningElement(node, opts) and t.assertJSXOpeningElement(node, opts).

Aliases: JSX, Immutable

• name: JSXIdentifier | JSXMemberExpression (required)
• attributes: Array<JSXAttribute | JSXSpreadAttribute> (required)
• selfClosing: boolean (default: false)

---

jSXSpreadAttribute

t.jSXSpreadAttribute(argument)

See also t.isJSXSpreadAttribute(node, opts) and t.assertJSXSpreadAttribute(node, opts).

Aliases: JSX

• argument: Expression (required)

---

jSXSpreadChild

t.jSXSpreadChild(expression)

See also t.isJSXSpreadChild(node, opts) and t.assertJSXSpreadChild(node, opts).

Aliases: JSX, Immutable

• expression: Expression (required)

---

jSXText

t.jSXText(value)

See also t.isJSXText(node, opts) and t.assertJSXText(node, opts).

Aliases: JSX, Immutable

• value: string (required)

---

labeledStatement

t.labeledStatement(label, body)

See also t.isLabeledStatement(node, opts) and t.assertLabeledStatement(node, opts).

Aliases: Statement

• label: Identifier (required)
• body: Statement (required)

---

logicalExpression

t.logicalExpression(operator, left, right)

See also t.isLogicalExpression(node, opts) and t.assertLogicalExpression(node, opts).

Aliases: Binary, Expression

• operator: '||' | '&&' (required)
• left: Expression (required)
• right: Expression (required)

---

memberExpression

t.memberExpression(object, property, computed)

See also t.isMemberExpression(node, opts) and t.assertMemberExpression(node, opts).

Aliases: Expression, LVal

• object: Expression (required)
• propertyif computed then Expression else Identifier (required)
• computed: boolean (default: false)

---

metaProperty

t.metaProperty(meta, property)

See also t.isMetaProperty(node, opts) and t.assertMetaProperty(node, opts).

Aliases: Expression

• meta: string (required)
• property: string (required)

---

mixedTypeAnnotation

t.mixedTypeAnnotation()

See also t.isMixedTypeAnnotation(node, opts) and t.assertMixedTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

newExpression

t.newExpression(callee, arguments)

See also t.isNewExpression(node, opts) and t.assertNewExpression(node, opts).

Aliases: Expression

• callee: Expression (required)
• arguments: Array<Expression | SpreadElement> (required)

---

noop

t.noop()

See also t.isNoop(node, opts) and t.assertNoop(node, opts).

---

nullLiteral

t.nullLiteral()

See also t.isNullLiteral(node, opts) and t.assertNullLiteral(node, opts).

Aliases: Expression, Pureish, Literal, Immutable

---

nullLiteralTypeAnnotation

t.nullLiteralTypeAnnotation()

See also t.isNullLiteralTypeAnnotation(node, opts) and t.assertNullLiteralTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

nullableTypeAnnotation

t.nullableTypeAnnotation(typeAnnotation)

See also t.isNullableTypeAnnotation(node, opts) and t.assertNullableTypeAnnotation(node, opts).

Aliases: Flow

• typeAnnotation (required)

---

numberTypeAnnotation

t.numberTypeAnnotation()

See also t.isNumberTypeAnnotation(node, opts) and t.assertNumberTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

---

numericLiteral

t.numericLiteral(value)

See also t.isNumericLiteral(node, opts) and t.assertNumericLiteral(node, opts).

Aliases: Expression, Pureish, Literal, Immutable

• value: number (required)

---

numericLiteralTypeAnnotation

t.numericLiteralTypeAnnotation()

See also t.isNumericLiteralTypeAnnotation(node, opts) and t.assertNumericLiteralTypeAnnotation(node, opts).

Aliases: Flow

---

objectExpression

t.objectExpression(properties)

See also t.isObjectExpression(node, opts) and t.assertObjectExpression(node, opts).

Aliases: Expression

• properties: Array<ObjectMethod | ObjectProperty | SpreadProperty> (required)

---

objectMethod

t.objectMethod(kind, key, params, body, computed)

See also t.isObjectMethod(node, opts) and t.assertObjectMethod(node, opts).

Aliases: UserWhitespacable, Function, Scopable, BlockParent, FunctionParent, Method, ObjectMember

• kind: "method" | "get" | "set" (default: 'method')
• keyif computed then Expression else Identifier | Literal (required)
• params (required)
• body: BlockStatement (required)
• computed: boolean (default: false)
• async: boolean (default: false)
• decorators: Array<Decorator> (default: null)
• generator: boolean (default: false)
• returnType (default: null)
• typeParameters (default: null)

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objectPattern

t.objectPattern(properties, typeAnnotation)

See also t.isObjectPattern(node, opts) and t.assertObjectPattern(node, opts).

Aliases: Pattern, LVal

• properties: Array<RestProperty | Property> (required)
• typeAnnotation (required)
• decorators: Array<Decorator> (default: null)

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objectProperty

t.objectProperty(key, value, computed, shorthand, decorators)

See also t.isObjectProperty(node, opts) and t.assertObjectProperty(node, opts).

Aliases: UserWhitespacable, Property, ObjectMember

• keyif computed then Expression else Identifier | Literal (required)
• value: Expression | Pattern | RestElement (required)
• computed: boolean (default: false)
• shorthand: boolean (default: false)
• decorators: Array<Decorator> (default: null)

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objectTypeAnnotation

t.objectTypeAnnotation(properties, indexers, callProperties)

See also t.isObjectTypeAnnotation(node, opts) and t.assertObjectTypeAnnotation(node, opts).

Aliases: Flow

• properties (required)
• indexers (required)
• callProperties (required)

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objectTypeCallProperty

t.objectTypeCallProperty(value)

See also t.isObjectTypeCallProperty(node, opts) and t.assertObjectTypeCallProperty(node, opts).

Aliases: Flow, UserWhitespacable

• value (required)

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objectTypeIndexer

t.objectTypeIndexer(id, key, value)

See also t.isObjectTypeIndexer(node, opts) and t.assertObjectTypeIndexer(node, opts).

Aliases: Flow, UserWhitespacable

• id (required)
• key (required)
• value (required)

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objectTypeProperty

t.objectTypeProperty(key, value)

See also t.isObjectTypeProperty(node, opts) and t.assertObjectTypeProperty(node, opts).

Aliases: Flow, UserWhitespacable

• key (required)
• value (required)

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objectTypeSpreadProperty

t.objectTypeSpreadProperty(argument)

See also t.isObjectTypeSpreadProperty(node, opts) and t.assertObjectTypeSpreadProperty(node, opts).

Aliases: Flow, UserWhitespacable

• argument (required)

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opaqueType

t.opaqueType(id, typeParameters, impltype, supertype)

See also t.isOpaqueType(node, opts) and t.assertOpaqueType(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• impltype (required)
• supertype (required)

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parenthesizedExpression

t.parenthesizedExpression(expression)

See also t.isParenthesizedExpression(node, opts) and t.assertParenthesizedExpression(node, opts).

Aliases: Expression, ExpressionWrapper

• expression: Expression (required)

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program

t.program(body, directives)

See also t.isProgram(node, opts) and t.assertProgram(node, opts).

Aliases: Scopable, BlockParent, Block, FunctionParent

• body: Array<Statement> (required)
• directives: Array<Directive> (default: [])

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qualifiedTypeIdentifier

t.qualifiedTypeIdentifier(id, qualification)

See also t.isQualifiedTypeIdentifier(node, opts) and t.assertQualifiedTypeIdentifier(node, opts).

Aliases: Flow

• id (required)
• qualification (required)

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regExpLiteral

t.regExpLiteral(pattern, flags)

See also t.isRegExpLiteral(node, opts) and t.assertRegExpLiteral(node, opts).

Aliases: Expression, Literal

• pattern: string (required)
• flags: string (default: '')

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restElement

t.restElement(argument, typeAnnotation)

See also t.isRestElement(node, opts) and t.assertRestElement(node, opts).

Aliases: LVal

• argument: LVal (required)
• typeAnnotation (required)
• decorators: Array<Decorator> (default: null)

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restProperty

t.restProperty(argument)

See also t.isRestProperty(node, opts) and t.assertRestProperty(node, opts).

Aliases: UnaryLike

• argument: LVal (required)

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returnStatement

t.returnStatement(argument)

See also t.isReturnStatement(node, opts) and t.assertReturnStatement(node, opts).

Aliases: Statement, Terminatorless, CompletionStatement

• argument: Expression (default: null)

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sequenceExpression

t.sequenceExpression(expressions)

See also t.isSequenceExpression(node, opts) and t.assertSequenceExpression(node, opts).

Aliases: Expression

• expressions: Array<Expression> (required)

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spreadElement

t.spreadElement(argument)

See also t.isSpreadElement(node, opts) and t.assertSpreadElement(node, opts).

Aliases: UnaryLike

• argument: Expression (required)

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spreadProperty

t.spreadProperty(argument)

See also t.isSpreadProperty(node, opts) and t.assertSpreadProperty(node, opts).

Aliases: UnaryLike

• argument: Expression (required)

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stringLiteral

t.stringLiteral(value)

See also t.isStringLiteral(node, opts) and t.assertStringLiteral(node, opts).

Aliases: Expression, Pureish, Literal, Immutable

• value: string (required)

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stringLiteralTypeAnnotation

t.stringLiteralTypeAnnotation()

See also t.isStringLiteralTypeAnnotation(node, opts) and t.assertStringLiteralTypeAnnotation(node, opts).

Aliases: Flow

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stringTypeAnnotation

t.stringTypeAnnotation()

See also t.isStringTypeAnnotation(node, opts) and t.assertStringTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

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super

t.super()

See also t.isSuper(node, opts) and t.assertSuper(node, opts).

Aliases: Expression

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switchCase

t.switchCase(test, consequent)

See also t.isSwitchCase(node, opts) and t.assertSwitchCase(node, opts).

• test: Expression (default: null)
• consequent: Array<Statement> (required)

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switchStatement

t.switchStatement(discriminant, cases)

See also t.isSwitchStatement(node, opts) and t.assertSwitchStatement(node, opts).

Aliases: Statement, BlockParent, Scopable

• discriminant: Expression (required)
• cases: Array<SwitchCase> (required)

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taggedTemplateExpression

t.taggedTemplateExpression(tag, quasi)

See also t.isTaggedTemplateExpression(node, opts) and t.assertTaggedTemplateExpression(node, opts).

Aliases: Expression

• tag: Expression (required)
• quasi: TemplateLiteral (required)

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templateElement

t.templateElement(value, tail)

See also t.isTemplateElement(node, opts) and t.assertTemplateElement(node, opts).

• value (required)
• tail: boolean (default: false)

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templateLiteral

t.templateLiteral(quasis, expressions)

See also t.isTemplateLiteral(node, opts) and t.assertTemplateLiteral(node, opts).

Aliases: Expression, Literal

• quasis: Array<TemplateElement> (required)
• expressions: Array<Expression> (required)

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thisExpression

t.thisExpression()

See also t.isThisExpression(node, opts) and t.assertThisExpression(node, opts).

Aliases: Expression

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thisTypeAnnotation

t.thisTypeAnnotation()

See also t.isThisTypeAnnotation(node, opts) and t.assertThisTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

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throwStatement

t.throwStatement(argument)

See also t.isThrowStatement(node, opts) and t.assertThrowStatement(node, opts).

Aliases: Statement, Terminatorless, CompletionStatement

• argument: Expression (required)

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tryStatement

t.tryStatement(block, handler, finalizer)

See also t.isTryStatement(node, opts) and t.assertTryStatement(node, opts).

Aliases: Statement

• block (required)
• handler (default: null)
• finalizer: BlockStatement (default: null)
• body: BlockStatement (default: null)

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tupleTypeAnnotation

t.tupleTypeAnnotation(types)

See also t.isTupleTypeAnnotation(node, opts) and t.assertTupleTypeAnnotation(node, opts).

Aliases: Flow

• types (required)

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typeAlias

t.typeAlias(id, typeParameters, right)

See also t.isTypeAlias(node, opts) and t.assertTypeAlias(node, opts).

Aliases: Flow, FlowDeclaration, Statement, Declaration

• id (required)
• typeParameters (required)
• right (required)

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typeAnnotation

t.typeAnnotation(typeAnnotation)

See also t.isTypeAnnotation(node, opts) and t.assertTypeAnnotation(node, opts).

Aliases: Flow

• typeAnnotation (required)

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typeCastExpression

t.typeCastExpression(expression, typeAnnotation)

See also t.isTypeCastExpression(node, opts) and t.assertTypeCastExpression(node, opts).

Aliases: Flow, ExpressionWrapper, Expression

• expression (required)
• typeAnnotation (required)

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typeParameter

t.typeParameter(bound)

See also t.isTypeParameter(node, opts) and t.assertTypeParameter(node, opts).

Aliases: Flow

• bound (required)

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typeParameterDeclaration

t.typeParameterDeclaration(params)

See also t.isTypeParameterDeclaration(node, opts) and t.assertTypeParameterDeclaration(node, opts).

Aliases: Flow

• params (required)

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typeParameterInstantiation

t.typeParameterInstantiation(params)

See also t.isTypeParameterInstantiation(node, opts) and t.assertTypeParameterInstantiation(node, opts).

Aliases: Flow

• params (required)

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typeofTypeAnnotation

t.typeofTypeAnnotation(argument)

See also t.isTypeofTypeAnnotation(node, opts) and t.assertTypeofTypeAnnotation(node, opts).

Aliases: Flow

• argument (required)

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unaryExpression

t.unaryExpression(operator, argument, prefix)

See also t.isUnaryExpression(node, opts) and t.assertUnaryExpression(node, opts).

Aliases: UnaryLike, Expression

• operator: 'void' | 'delete' | '!' | '+' | '-' | '++' | '--' | '~' | 'typeof' (required)
• argument: Expression (required)
• prefix: boolean (default: true)

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unionTypeAnnotation

t.unionTypeAnnotation(types)

See also t.isUnionTypeAnnotation(node, opts) and t.assertUnionTypeAnnotation(node, opts).

Aliases: Flow

• types (required)

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updateExpression

t.updateExpression(operator, argument, prefix)

See also t.isUpdateExpression(node, opts) and t.assertUpdateExpression(node, opts).

Aliases: Expression

• operator: '++' | '--' (required)
• argument: Expression (required)
• prefix: boolean (default: false)

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variableDeclaration

t.variableDeclaration(kind, declarations)

See also t.isVariableDeclaration(node, opts) and t.assertVariableDeclaration(node, opts).

Aliases: Statement, Declaration

• kind: "var" | "let" | "const" (required)
• declarations: Array<VariableDeclarator> (required)

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variableDeclarator

t.variableDeclarator(id, init)

See also t.isVariableDeclarator(node, opts) and t.assertVariableDeclarator(node, opts).

• id: LVal (required)
• init: Expression (default: null)

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voidTypeAnnotation

t.voidTypeAnnotation()

See also t.isVoidTypeAnnotation(node, opts) and t.assertVoidTypeAnnotation(node, opts).

Aliases: Flow, FlowBaseAnnotation

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whileStatement

t.whileStatement(test, body)

See also t.isWhileStatement(node, opts) and t.assertWhileStatement(node, opts).

Aliases: Statement, BlockParent, Loop, While, Scopable

• test: Expression (required)
• body: BlockStatement | Statement (required)

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withStatement

t.withStatement(object, body)

See also t.isWithStatement(node, opts) and t.assertWithStatement(node, opts).

Aliases: Statement

• object (required)
• body: BlockStatement | Statement (required)

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yieldExpression

t.yieldExpression(argument, delegate)

See also t.isYieldExpression(node, opts) and t.assertYieldExpression(node, opts).

Aliases: Expression, Terminatorless

• argument: Expression (default: null)
• delegate: boolean (default: false)

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