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estree-util-value-to-estree
Convert a JavaScript value to an ESTree expression.
Table of Contents
Installation
npm install estree-util-value-to-estree
Usage
This package converts a JavaScript value to an ESTree expression for values that can be constructed without the need for a context.
Currently the following types are supported:
bigint
boolean
null
number
(Including Infinity and NaN)string
symbol
(shared and well-known)object
- null-prototype
Object
undefined
Array
BigInt64Array
BigUint64Array
Boolean
Buffer
Date
Float32Array
Float64Array
Int16Array
Int32Array
Int8Array
Map
Number
RegExp
Set
String
Uint16Array
Uint32Array
Uint8Array
Uint8ClampedArray
URL
URLSearchParams
If options.instanceAsObject
is set to true
, other objects are turned into plain object.
import assert from 'node:assert/strict'
import { valueToEstree } from 'estree-util-value-to-estree'
const result = valueToEstree({
null: null,
undefined,
string: 'Hello world!',
number: 42,
negativeNumber: -1337,
infinity: Number.POSITIVE_INFINITY,
notANumber: Number.NaN,
regex: /\w+/i,
date: new Date('1970-01-01'),
array: ['I’m an array item!'],
object: { nested: 'value' }
})
assert.deepEqual(result, {
type: 'ObjectExpression',
properties: [
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'null' },
value: { type: 'Literal', value: null }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'undefined' },
value: { type: 'Identifier', name: 'undefined' }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'string' },
value: { type: 'Literal', value: 'Hello world!' }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'number' },
value: { type: 'Literal', value: 42 }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'negativeNumber' },
value: {
type: 'UnaryExpression',
operator: '-',
prefix: true,
argument: { type: 'Literal', value: 1337 }
}
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'infinity' },
value: { type: 'Identifier', name: 'Infinity' }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'notANumber' },
value: { type: 'Identifier', name: 'NaN' }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'regex' },
value: {
type: 'Literal',
value: /\w+/i,
regex: { pattern: '\\w+', flags: 'i' }
}
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'date' },
value: {
type: 'NewExpression',
callee: { type: 'Identifier', name: 'Date' },
arguments: [{ type: 'Literal', value: 0 }]
}
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'array' },
value: {
type: 'ArrayExpression',
elements: [{ type: 'Literal', value: 'I’m an array item!' }]
}
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'object' },
value: {
type: 'ObjectExpression',
properties: [
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'nested' },
value: { type: 'Literal', value: 'value' }
}
]
}
}
]
})
class Point {
line: number
column: number
constructor(line: number, column: number) {
this.line = line
this.column = column
}
}
// Normally complex objects throw.
assert.throws(() => valueToEstree(new Point(2, 3)))
// `instanceAsObject: true` treats them as plain objects.
assert.deepEqual(valueToEstree(new Point(2, 3), { instanceAsObject: true }), {
type: 'ObjectExpression',
properties: [
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'line' },
value: { type: 'Literal', value: 2 }
},
{
type: 'Property',
method: false,
shorthand: false,
computed: false,
kind: 'init',
key: { type: 'Literal', value: 'column' },
value: { type: 'Literal', value: 3 }
}
]
})
API
This API exports the function valueToEstree
.
valueToEstree(value, options?)
Convert a value to an ESTree node.
options
instanceAsObject
(boolean, default:false
) — If true, treat objects that have a prototype as plain objects.preserveReferences
(boolean, default:false
) — If true, preserve references to the same object found within the input. This also allows to serialize recursive structures. If needed, the resulting expression will be an iife.
Compatibility
This project is compatible with Node.js 16 or greater.