discourse/app/assets/javascripts/polyfills.js

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries
if (!Object.entries) {
  Object.entries = function(obj) {
    var ownProps = Object.keys(obj),
      i = ownProps.length,
      resArray = new Array(i); // preallocate the Array
    while (i--) resArray[i] = [ownProps[i], obj[ownProps[i]]];

    return resArray;
  };
}

// adapted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries
// missing in ie only
if (!Object.values) {
  Object.values = function(obj) {
    var ownProps = Object.keys(obj),
      i = ownProps.length,
      resArray = new Array(i); // preallocate the Array
    while (i--) resArray[i] = obj[ownProps[i]];

    return resArray;
  };
}

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
if (typeof Object.assign !== "function") {
  // Must be writable: true, enumerable: false, configurable: true
  Object.defineProperty(Object, "assign", {
    value: function assign(target) {
      // .length of function is 2
      "use strict";
      if (target == null) {
        // TypeError if undefined or null
        throw new TypeError("Cannot convert undefined or null to object");
      }

      var to = Object(target);

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

        if (nextSource != null) {
          // Skip over if undefined or null
          for (var 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
  });
}

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes#Polyfill
/* eslint-disable */
if (!Array.prototype.includes) {
  Object.defineProperty(Array.prototype, "includes", {
    value: function(searchElement, fromIndex) {
      if (this == null) {
        throw new TypeError('"this" is null or not defined');
      }

      // 1. Let O be ? ToObject(this value).
      var o = Object(this);

      // 2. Let len be ? ToLength(? Get(O, "length")).
      var len = o.length >>> 0;

      // 3. If len is 0, return false.
      if (len === 0) {
        return false;
      }

      // 4. Let n be ? ToInteger(fromIndex).
      //    (If fromIndex is undefined, this step produces the value 0.)
      var n = fromIndex | 0;

      // 5. If n ≥ 0, then
      //  a. Let k be n.
      // 6. Else n < 0,
      //  a. Let k be len + n.
      //  b. If k < 0, let k be 0.
      var k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

      function sameValueZero(x, y) {
        return (
          x === y ||
          (typeof x === "number" &&
            typeof y === "number" &&
            isNaN(x) &&
            isNaN(y))
        );
      }

      // 7. Repeat, while k < len
      while (k < len) {
        // a. Let elementK be the result of ? Get(O, ! ToString(k)).
        // b. If SameValueZero(searchElement, elementK) is true, return true.
        if (sameValueZero(o[k], searchElement)) {
          return true;
        }
        // c. Increase k by 1.
        k++;
      }

      // 8. Return false
      return false;
    }
  });
}

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes#Polyfill
if (!String.prototype.includes) {
  Object.defineProperty(String.prototype, "includes", {
    value: function(search, start) {
      if (typeof start !== "number") {
        start = 0;
      }

      if (start + search.length > this.length) {
        return false;
      } else {
        return this.indexOf(search, start) !== -1;
      }
    }
  });
}

// https://tc39.github.io/ecma262/#sec-array.prototype.find
if (!Array.prototype.find) {
  Object.defineProperty(Array.prototype, "find", {
    value: function(predicate) {
      // 1. Let O be ? ToObject(this value).
      if (this == null) {
        throw new TypeError('"this" is null or not defined');
      }

      var o = Object(this);

      // 2. Let len be ? ToLength(? Get(O, "length")).
      var len = o.length >>> 0;

      // 3. If IsCallable(predicate) is false, throw a TypeError exception.
      if (typeof predicate !== "function") {
        throw new TypeError("predicate must be a function");
      }

      // 4. If thisArg was supplied, let T be thisArg; else let T be undefined.
      var thisArg = arguments[1];

      // 5. Let k be 0.
      var k = 0;

      // 6. Repeat, while k < len
      while (k < len) {
        // a. Let Pk be ! ToString(k).
        // b. Let kValue be ? Get(O, Pk).
        // c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
        // d. If testResult is true, return kValue.
        var kValue = o[k];
        if (predicate.call(thisArg, kValue, k, o)) {
          return kValue;
        }
        // e. Increase k by 1.
        k++;
      }

      // 7. Return undefined.
      return undefined;
    },
    configurable: true,
    writable: true
  });
}

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/flags#Polyfill
if (RegExp.prototype.flags === undefined) {
  Object.defineProperty(RegExp.prototype, "flags", {
    configurable: true,
    get: function() {
      return this.toString().match(/[gimsuy]*$/)[0];
    }
  });
}

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from
// Production steps of ECMA-262, Edition 6, 22.1.2.1
if (!Array.from) {
  Array.from = (function() {
    var toStr = Object.prototype.toString;
    var isCallable = function(fn) {
      return typeof fn === "function" || toStr.call(fn) === "[object Function]";
    };
    var toInteger = function(value) {
      var number = Number(value);
      if (isNaN(number)) {
        return 0;
      }
      if (number === 0 || !isFinite(number)) {
        return number;
      }
      return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number));
    };
    var maxSafeInteger = Math.pow(2, 53) - 1;
    var toLength = function(value) {
      var len = toInteger(value);
      return Math.min(Math.max(len, 0), maxSafeInteger);
    };

    // The length property of the from method is 1.
    return function from(arrayLike /*, mapFn, thisArg */) {
      // 1. Let C be the this value.
      var C = this;

      // 2. Let items be ToObject(arrayLike).
      var items = Object(arrayLike);

      // 3. ReturnIfAbrupt(items).
      if (arrayLike == null) {
        throw new TypeError(
          "Array.from requires an array-like object - not null or undefined"
        );
      }

      // 4. If mapfn is undefined, then let mapping be false.
      var mapFn = arguments.length > 1 ? arguments[1] : void undefined;
      var T;
      if (typeof mapFn !== "undefined") {
        // 5. else
        // 5. a If IsCallable(mapfn) is false, throw a TypeError exception.
        if (!isCallable(mapFn)) {
          throw new TypeError(
            "Array.from: when provided, the second argument must be a function"
          );
        }

        // 5. b. If thisArg was supplied, let T be thisArg; else let T be undefined.
        if (arguments.length > 2) {
          T = arguments[2];
        }
      }

      // 10. Let lenValue be Get(items, "length").
      // 11. Let len be ToLength(lenValue).
      var len = toLength(items.length);

      // 13. If IsConstructor(C) is true, then
      // 13. a. Let A be the result of calling the [[Construct]] internal method
      // of C with an argument list containing the single item len.
      // 14. a. Else, Let A be ArrayCreate(len).
      var A = isCallable(C) ? Object(new C(len)) : new Array(len);

      // 16. Let k be 0.
      var k = 0;
      // 17. Repeat, while k < len… (also steps a - h)
      var kValue;
      while (k < len) {
        kValue = items[k];
        if (mapFn) {
          A[k] =
            typeof T === "undefined"
              ? mapFn(kValue, k)
              : mapFn.call(T, kValue, k);
        } else {
          A[k] = kValue;
        }
        k += 1;
      }
      // 18. Let putStatus be Put(A, "length", len, true).
      A.length = len;
      // 20. Return A.
      return A;
    };
  })();
}

/* eslint-enable */