estree-util-value-to-estree

Convert a JavaScript value to an ESTree expression.

Installation
Usage
API
- valueToEstree(value, options?)
Compatibility
License

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:

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.

License

MIT © Remco Haszing

Feature Request: Custom Handlers

Feature

I want to be able to customise how valueToEstree converts an object to estree.

The solution I'm thinking of, would be providing an handlers option for handling different types.

For example, disable it only for objects containing a special property.

valueToEstree(value, {
  handlers: {
    object: (v) => isHast(v)? hastToEstree(v) : undefined
  |
})

When undefined is returned, use the default behavour.

Additional context

I was trying to inject an object as the prop of a MDX element. Now I have an object like:

{
  name: "Hello",
  description: "Markdown Content"
}

to convert it into estree, I have to first compile the markdown content description to HAST tree, and use hast-util-to-estree to make it an estree.

{
  name: "Hello",
  description: { ... } // ES Tree
}

Now I will use this utility to convert the whole object into estree. But it apparently will treat the description property as an ordinary object, hence it can't give my desired result.

I fixed it by manipulating the estree afterwards, would like to see if this can be done with this library.

remcohaszing / estree-util-value-to-estree Goto Github PK