@putout/plugin-typescript

@putout/plugin-typescript

TypeScript is JavaScript with syntax for types.

(c) typescriptcriptlang.org

🐊Putout plugin adds ability to transform TypeScript code. Enabled by default for ts and tsx files.

Install

npm i putout @putout/plugin-typescript -D

Options

{
    "rules": {
        "typescript/apply-as-type-assertion": "on",
        "typescript/apply-utility-types": "on",
        "typescript/convert-generic-to-shorthand": "on",
        "typescript/remove-duplicates-from-union": "on",
        "typescript/remove-duplicates-interface-keys": "on",
        "typescript/remove-useless-types-from-constants": "on",
        "typescript/remove-unused-types": "on",
        "typescript/remove-useless-types": "on",
        "typescript/remove-useless-mapped-types": "on"
    }
}

Rules

apply-as-type-assertion

❌ Example of incorrect code

const boundaryElement = <HTMLElement>e.target;

✅ Example of correct code

const boundaryElement1 = e.target as HTMLElement;

apply-utility-types

❌ Example of incorrect code

type SuperType1 = {
    [Key in keyof Type]?: Type[Key];
};

✅ Example of correct code

type SuperType1 = Partial<Type>;

convert-generic-to-shorthand

There is no difference at all. Type[] is the shorthand syntax for an array of Type. Array<Type> is the generic syntax. They are completely equivalent.

(c) https://stackoverflow.com/a/36843084/4536327

Convert generic to shorthand.

❌ Example of incorrect code

interface A {
    x: Array<X>;
    y: Array<Y>;
}

✅ Example of correct code

interface A {
    x: X[];
    y: Y[];
}

remove-duplicates-from-union

❌ Example of incorrect code

type x = boolean[]
    | A
    | string
    | A
    | string[]
    | boolean[];

✅ Example of correct code

type x = boolean[]
    | A
    | string
    | string[];

remove-useless-types-from-constants

❌ Example of incorrect code

const x: any = 5;

✅ Example of correct code

const x = 5;

remove-unused-types

❌ Example of incorrect code

type n = number;
type s = string;

const x: n = 5;

✅ Example of correct code

type n = number;

const x: n = 5;

remove-useless-types

❌ Example of incorrect code

type oldType = {
    a: number,
    b: string,
};

type newType = oldType;

const x: newType = {
    a: 5,
    b: 'hello',
};

✅ Example of correct code

type oldType = {
    a: number,
    b: string,
};

const x: oldType = {
    a: 5,
    b: 'hello',
};

remove-useless-mapped-types

Rmove useless mapped types.

❌ Example of incorrect code

type SuperType = {
    [Key in keyof Type]: Type[Key];
};

✅ Example of correct code

type SuperType = Type;

remove-useless-mapping-modifiers

Remove useless mapping modifiers.

❌ Example of incorrect code

type SuperType = {
    [Key in keyof Type]+?: Type[Key];
};

✅ Example of correct code

type SuperType = {
    [Key in keyof Type]?: Type[Key];
};

remove-duplicate-interface-keys

❌ Example of incorrect code

interface Hello {
    'hello': any
    'hello': string
}

✅ Example of correct code

interface Hello {
    'hello': string
}

License

MIT