2.0.3 • Public • Published

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code-stringify is the node.js module that converts JavaScript variables into source codes with indents and styles.

Unlike JSON.stringify, code-stringify also deals with reference(object) types of variables, and it converts JavaScript variables into strings of codes, not JSON.


  • Primative variables
  • Regular expressions
  • Functions
  • Arrays
  • Your custom formatter


npm i code-stringify


const fs = require('fs')
const stringify = require('code-stringify')
const obj = {
  '0': 1,
  'a': function(n){return n;},
  'b': 1,
  'c-d': 3
// So you can use code-stringify to save your javascript variables into a file:
  `module.exports = ${stringify(obj, null, 2)}`

Then 'output.js' will look like:

module.exports = {
  0: 1,
  a: function(n){return n;},
  b: 1,
  'c-d': 3

stringify(subject, replacer, space, indent): string

subject any

The subject to be stringified

replacer Function(key, value) | Array

The replacer argument acts just like the second parameter of JSON.stringify.

A function that alters the behavior of the stringification process, or an array of String and Number objects that serve as a whitelist for selecting/filtering the properties of the value object to be included in the JSON string. If this value is null or not provided, all properties of the object are included in the resulting JSON string.

  a: 1,
  b: 2
}, function (key, value) {
  return key === 'b'
    ? undefined
    : value
// '{a:1}'
space number | string

The space argument acts just like the third parameter of JSON.stringify.

indent number | string

Defaults to 0

The code indent for the entire subject. If indent === 4, then the content of the output.js in the first example will be:

    module.exports = {
      0: 1,
      a: function (n){return n;},
      b: 1,
      'c-d': 3

new stringify.Code(string)

We could use new code.Code(code_string) to define an already-stringified property.

So, see the example below:

const output = `module.exports = ${stringify({
  a: 1,
  'foo-bar': 2,
  foo: new stringify.Code('(function(a){return a})(3)')
saveFile(output, 'output.js')

And the output.js will be:

module.exports = {
  a: 1,
  'foo-bar': 2,
  foo: (function(a){return a})(3)


// `stringify.STRINGIFY_SYMBOL` equals to
stringify.STRINGIFY_SYMBOL = Symbol.for('code.stringify.custom')

If an object[stringify.STRINGIFY_SYMBOL] is a function, then the function will be used as the stringifier of the object.

const monkey = {
  iam: {
    [Symbol.for('code.stringify.custom')] () {
      return '"monkey king"'
// {iam:"monkey king"}

Versus JSON.stringify()

  • JSON.stringify makes JSON.
  • code-stringify makes JavaScript code.

Advanced Section

const {
= require('code-stringify')

new Stringifier(options)

new in 2.0.0

The constructor Stringifier allows us to take more control of the stringifer.

  • options Object
    • replacer? (Function | Array)=null
    • space? (number | string)=0 Defaults to 0 which indicates there should be no spaces.
    • quote? ' | " the quote character for strings. Defaults to '.
    • useNumberKey? boolean=true uses number key of an object if possible


new Stringifier().stringify({'1': 1, '2b': 2})
// {1:1,'2b':2}
new Stringifier({
  useNumberKey: false
}).stringify({'1': 1, '2b': 2})
// {'1':1:'2b':2}

stringifier.stringify(subject, indent = 0): string

  • indent? (number | string)=0

Returns the JavaScript code string.

stringifier.register(customStringifier): this

  • customStringifier CustomStringifier
interface CustomStringifier {
  // Test if we could use the custom stringifier
  test: Function (subject)boolean
  // If the test method returns true,
  // then the stringify method will be used.
  // Inside the method, we can access the `Stringifier` instance by `this` object, so that we can use the utility methods below
  stringify: Function(subject, indent, options)string

Register a custom stringifier for certain data type.

class King {
  constructor (name) {
    this._name = name
  selfIntroduce () {
    return `[king ${this._name}]`
new Stringifier().register({
  test (value) {
    return value instanceof Monkey
  stringify (value) {
    return this.string(value.selfIntroduce())
  dinosaur: 'Godzilla',
  ape: new King('Kong')
// {dinasaur:'Godzilla',ape:'[king Kong]'}


CODE_STRINGIFY_CUSTOM is a built-in CustomStringifier to support stringify.STRINGIFY_SYMBOL.

And a new Stringifier is not registered CODE_STRINGIFY_CUSTOM by default.

Utility methods

The following methods has no type checking and fault tolerance

Make sure every argument that passed into the methods has been type-checked


  • string string

Stringify a string

stringifier.object(object, indent)

  • object Object

Stringify a string

stringifier.array(array, indent)

  • array Array

Stringify an array


  • string key

Stringify a property of an object.

Known Issues

  • space parameter could not affect the code indent inside functions.
  • Could not deal with variable scope so far.

Those issues or tasks which should be done to enhance the module might be fixed in the future. Or there will be a million thanks if you fork and contribute ~~

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npm i code-stringify

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  • kael