File Explorer

1'use strict';2 3/* eslint no-invalid-this: 1 */4 5var ERROR_MESSAGE = 'Function.prototype.bind called on incompatible ';6var toStr = Object.prototype.toString;7var max = Math.max;8var funcType = '[object Function]';9 10var concatty = function concatty(a, b) {11    var arr = [];12 13    for (var i = 0; i < a.length; i += 1) {14        arr[i] = a[i];15    }16    for (var j = 0; j < b.length; j += 1) {17        arr[j + a.length] = b[j];18    }19 20    return arr;21};22 23var slicy = function slicy(arrLike, offset) {24    var arr = [];25    for (var i = offset || 0, j = 0; i < arrLike.length; i += 1, j += 1) {26        arr[j] = arrLike[i];27    }28    return arr;29};30 31var joiny = function (arr, joiner) {32    var str = '';33    for (var i = 0; i < arr.length; i += 1) {34        str += arr[i];35        if (i + 1 < arr.length) {36            str += joiner;37        }38    }39    return str;40};41 42module.exports = function bind(that) {43    var target = this;44    if (typeof target !== 'function' || toStr.apply(target) !== funcType) {45        throw new TypeError(ERROR_MESSAGE + target);46    }47    var args = slicy(arguments, 1);48 49    var bound;50    var binder = function () {51        if (this instanceof bound) {52            var result = target.apply(53                this,54                concatty(args, arguments)55            );56            if (Object(result) === result) {57                return result;58            }59            return this;60        }61        return target.apply(62            that,63            concatty(args, arguments)64        );65 66    };67 68    var boundLength = max(0, target.length - args.length);69    var boundArgs = [];70    for (var i = 0; i < boundLength; i++) {71        boundArgs[i] = '$' + i;72    }73 74    bound = Function('binder', 'return function (' + joiny(boundArgs, ',') + '){ return binder.apply(this,arguments); }')(binder);75 76    if (target.prototype) {77        var Empty = function Empty() {};78        Empty.prototype = target.prototype;79        bound.prototype = new Empty();80        Empty.prototype = null;81    }82 83    return bound;84};85