PHP's json_encode in JavaScript

module.exports = functionjson_encode (mixedVal) { // eslint-disable-line camelcase
//       discuss at: https://phpjs.org/functions/json_encode/
//      original by: Public Domain (https://www.json.org/json2.js)
// reimplemented by: Kevin van Zonneveld (https://kevin.vanzonneveld.net)
//      improved by: Michael White
//         input by: felix
//      bugfixed by: Brett Zamir (https://brett-zamir.me)
//        example 1: json_encode('Kevin')
//        returns 1: '"Kevin"'
/*
    https://www.JSON.org/json2.js
    2008-11-19
    Public Domain.
    NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
    See https://www.JSON.org/js.html
  */
const $global = (typeofwindow !== 'undefined' ? window : global)
  $global.$locutus = $global.$locutus || {}
const $locutus = $global.$locutus
  $locutus.php = $locutus.php || {}
const json = $global.JSON
let retVal
try {
if (typeof json === 'object' && typeof json.stringify === 'function') {
// Errors will not be caught here if our own equivalent to resource
      retVal = json.stringify(mixedVal)
if (retVal === undefined) {
thrownewSyntaxError('json_encode')
      }
return retVal
    }
const value = mixedVal
const quote = function (string) {
const escapeChars = [
'\u0000-\u001f',
'\u007f-\u009f',
'\u00ad',
'\u0600-\u0604',
'\u070f',
'\u17b4',
'\u17b5',
'\u200c-\u200f',
'\u2028-\u202f',
'\u2060-\u206f',
'\ufeff',
'\ufff0-\uffff'
      ].join('')
const escapable = newRegExp('[\\"' + escapeChars + ']', 'g')
const meta = {
// table of character substitutions
'\b': '\\b',
'\t': '\\t',
'\n': '\\n',
'\f': '\\f',
'\r': '\\r',
'"': '\\"',
'\\': '\\\\'
      }
      escapable.lastIndex = 0
return escapable.test(string)
        ? '"' + string.replace(escapable, function (a) {
const c = meta[a]
returntypeof c === 'string' ? c : '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4)
        }) + '"'
        : '"' + string + '"'
    }
var _str = function (key, holder) {
let gap = ''
const indent = '    '
// The loop counter.
let i = 0
// The member key.
let k = ''
// The member value.
let v = ''
let length = 0
const mind = gap
let partial = []
let value = holder[key]
// If the value has a toJSON method, call it to obtain a replacement value.
if (value && typeof value === 'object' && typeof value.toJSON === 'function') {
        value = value.toJSON(key)
      }
// What happens next depends on the value's type.
switch (typeof value) {
case'string':
return quote(value)
case'number':
// JSON numbers must be finite. Encode non-finite numbers as null.
returnisFinite(value) ? String(value) : 'null'
case'boolean':
// If the value is a boolean or null, convert it to a string.
returnString(value)
case'object':
// If the type is 'object', we might be dealing with an object or an array or
// null.
// Due to a specification blunder in ECMAScript, typeof null is 'object',
// so watch out for that case.
if (!value) {
return'null'
          }
// Make an array to hold the partial results of stringifying this object value.
          gap += indent
          partial = []
// Is the value an array?
if (Object.prototype.toString.apply(value) === '[object Array]') {
// The value is an array. Stringify every element. Use null as a placeholder
// for non-JSON values.
            length = value.length
for (i = 0; i < length; i += 1) {
              partial[i] = _str(i, value) || 'null'
            }
// Join all of the elements together, separated with commas, and wrap them in
// brackets.
            v = partial.length === 0
              ? '[]'
              : gap
                ? '[\n' + gap + partial.join(',\n' + gap) + '\n' + mind + ']'
                : '[' + partial.join(',') + ']'
// gap = mind // not used
return v
          }
// Iterate through all of the keys in the object.
for (k in value) {
if (Object.hasOwnProperty.call(value, k)) {
              v = _str(k, value)
if (v) {
                partial.push(quote(k) + (gap ? ': ' : ':') + v)
              }
            }
          }
// Join all of the member texts together, separated with commas,
// and wrap them in braces.
          v = partial.length === 0
            ? '{}'
            : gap
              ? '{\n' + gap + partial.join(',\n' + gap) + '\n' + mind + '}'
              : '{' + partial.join(',') + '}'
// gap = mind // Not used
return v
case'undefined':
case'function':
default:
thrownewSyntaxError('json_encode')
      }
    }
// Make a fake root object containing our value under the key of ''.
// Return the result of stringifying the value.
return _str('', {
'': value
    })
  } catch (err) {
// @todo: ensure error handling above throws a SyntaxError in all cases where it could
// (i.e., when the JSON global is not available and there is an error)
if (!(err instanceofSyntaxError)) {
thrownewError('Unexpected error type in json_encode()')
    }
// usable by json_last_error()
    $locutus.php.last_error_json = 4
returnnull
  }
}