zx-editor/src/js/util/polyfill.js

ZxEditor is a HTML5 rich text editor

if (typeof Object.assign !== 'function') {
  // Must be writable: true, enumerable: false, configurable: true
  Object.defineProperty(Object, 'assign', {
    value: function assign (target, varArgs) { // .length of function is 2
      if (!target) { // TypeError if undefined or null
        throw new TypeError('Cannot convert undefined or null to object')
      }

      const to = Object(target)

      for (let index = 1; index < arguments.length; index++) {
        let nextSource = arguments[index]

        if (nextSource) { // Skip over if undefined or null
          for (let nextKey in nextSource) {
            // Avoid bugs when hasOwnProperty is shadowed
            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
              to[nextKey] = nextSource[nextKey]
            }
          }
        }
      }
      return to
    },
    writable: true,
    configurable: true
  })
}

// Production steps of ECMA-262, Edition 5, 15.4.4.14
// Reference: http://es5.github.io/#x15.4.4.14
if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(searchElement, fromIndex) {

    let k

    // 1. Let O be the result of calling ToObject passing
    //    the this value as the argument.
    if (!this) {
      throw new TypeError('"this" is null or not defined')
    }

    let O = Object(this)

    // 2. Let lenValue be the result of calling the Get
    //    internal method of O with the argument "length".
    // 3. Let len be ToUint32(lenValue).
    let len = O.length >>> 0

    // 4. If len is 0, return -1.
    if (len === 0) {
      return -1
    }

    // 5. If argument fromIndex was passed let n be
    //    ToInteger(fromIndex); else let n be 0.
    let n = +fromIndex || 0

    if (Math.abs(n) === Infinity) {
      n = 0
    }

    // 6. If n >= len, return -1.
    if (n >= len) {
      return -1
    }

    // 7. If n >= 0, then Let k be n.
    // 8. Else, n<0, Let k be len - abs(n).
    //    If k is less than 0, then let k be 0.
    k = Math.max(n >= 0 ? n : len - Math.abs(n), 0)

    // 9. Repeat, while k < len
    while (k < len) {
      // a. Let Pk be ToString(k).
      //   This is implicit for LHS operands of the in operator
      // b. Let kPresent be the result of calling the
      //    HasProperty internal method of O with argument Pk.
      //   This step can be combined with c
      // c. If kPresent is true, then
      //    i.  Let elementK be the result of calling the Get
      //        internal method of O with the argument ToString(k).
      //   ii.  Let same be the result of applying the
      //        Strict Equality Comparison Algorithm to
      //        searchElement and elementK.
      //  iii.  If same is true, return k.
      if (k in O && O[k] === searchElement) {
        return k
      }
      k++
    }
    return -1
  }
}

// Production steps of ECMA-262, Edition 5, 15.4.4.18
// Reference: http://es5.github.io/#x15.4.4.18
if (!Array.prototype.forEach) {

  Array.prototype.forEach = function (callback, thisArg) {

    let T, k

    if (!this) {
      throw new TypeError(' this is null or not defined')
    }

    // 1. Let O be the result of calling toObject() passing the
    // |this| value as the argument.
    let O = Object(this)

    // 2. Let lenValue be the result of calling the Get() internal
    // method of O with the argument "length".
    // 3. Let len be toUint32(lenValue).
    let len = O.length >>> 0

    // 4. If isCallable(callback) is false, throw a TypeError exception.
    // See: http://es5.github.com/#x9.11
    if (typeof callback !== "function") {
      throw new TypeError(callback + ' is not a function');
    }

    // 5. If thisArg was supplied, let T be thisArg; else let
    // T be undefined.
    if (arguments.length > 1) {
      T = thisArg
    }

    // 6. Let k be 0
    k = 0

    // 7. Repeat, while k < len
    while (k < len) {

      let kValue

      // a. Let Pk be ToString(k).
      //    This is implicit for LHS operands of the in operator
      // b. Let kPresent be the result of calling the HasProperty
      //    internal method of O with argument Pk.
      //    This step can be combined with c
      // c. If kPresent is true, then
      if (k in O) {

        // i. Let kValue be the result of calling the Get internal
        // method of O with argument Pk.
        kValue = O[k]

        // ii. Call the Call internal method of callback with T as
        // the this value and argument list containing kValue, k, and O.
        callback.call(T, kValue, k, O)
      }
      // d. Increase k by 1.
      k++
    }
    // 8. return undefined
  }
}