ts-expression-evaluator

ts-expression-evaluator

Context-based expression evaluator.

install

• npm npm install ts-expression-evaluator
• yarn yarn add ts-expression-evaluator

Quick start

import evaluate, { registerFunction } from 'ts-expression-evaluator'
const context = {
  id: 10,
  name: 'FED',
  count: 10,
  staffs: [{
    id: 1,
    name: 'Tina'
  }, {
    id: 2,
    name: 'James'
  }],
}

// math
evaluate('1+2') // 3

// eval from context
evaluate('name', context) // 'FED'
evaluate('staffs[0].name', context) // 'Tina'
evaluate('count + 10', context) // 20

// ===
evaluate('count === 11', context) // false

// register custom function
registerFunction('IF', (condition, ifTrue, ifFalse) => {
  return condition ? ifTrue : ifFalse;
})

evaluate('IF(name === 'FED', 'It\'s FED.', 'It\'s not FED.')') // It's FED.

// array filter
evaluate('staffs[this.id === 1]', context) // [{id: 1, name: 'Tina'}]

Details

Unary Operators

Operation	Symbol
Negate	!

Binary Operators

Operation	Symbol
Add, Concat	+
Subtract	-
Multiply	*
Divide	/

Logical Operators

Operation	Symbol
Logical AND	&&
Logical OR	||

Comparisons

Comparison	Symbol
Equal	==
Not equal	!=
Greater than	>
Greater than or equal	>=
Less than	<
Less than or equal	<=

Native Types

Type	Examples
Booleans	true, false
Strings	"Hello "user"", 'Hey there!'
Numerics	6, -7.2, 5, -3.14159
Arrays	['hello', 'world!']

API

evaluate(exp: string, context: object): any

registerFunction(name: string, func: Function): void

registerFunctions(funcs: {[key: string]: Function}): void

License

MIT