| 'use strict'; |
| |
| /* eslint no-invalid-this: 1 */ |
| |
| var ERROR_MESSAGE = 'Function.prototype.bind called on incompatible '; |
| var toStr = Object.prototype.toString; |
| var max = Math.max; |
| var funcType = '[object Function]'; |
| |
| var concatty = function concatty(a, b) { |
| var arr = []; |
| |
| for (var i = 0; i < a.length; i += 1) { |
| arr[i] = a[i]; |
| } |
| for (var j = 0; j < b.length; j += 1) { |
| arr[j + a.length] = b[j]; |
| } |
| |
| return arr; |
| }; |
| |
| var slicy = function slicy(arrLike, offset) { |
| var arr = []; |
| for (var i = offset || 0, j = 0; i < arrLike.length; i += 1, j += 1) { |
| arr[j] = arrLike[i]; |
| } |
| return arr; |
| }; |
| |
| var joiny = function (arr, joiner) { |
| var str = ''; |
| for (var i = 0; i < arr.length; i += 1) { |
| str += arr[i]; |
| if (i + 1 < arr.length) { |
| str += joiner; |
| } |
| } |
| return str; |
| }; |
| |
| module.exports = function bind(that) { |
| var target = this; |
| if (typeof target !== 'function' || toStr.apply(target) !== funcType) { |
| throw new TypeError(ERROR_MESSAGE + target); |
| } |
| var args = slicy(arguments, 1); |
| |
| var bound; |
| var binder = function () { |
| if (this instanceof bound) { |
| var result = target.apply( |
| this, |
| concatty(args, arguments) |
| ); |
| if (Object(result) === result) { |
| return result; |
| } |
| return this; |
| } |
| return target.apply( |
| that, |
| concatty(args, arguments) |
| ); |
| |
| }; |
| |
| var boundLength = max(0, target.length - args.length); |
| var boundArgs = []; |
| for (var i = 0; i < boundLength; i++) { |
| boundArgs[i] = '$' + i; |
| } |
| |
| bound = Function('binder', 'return function (' + joiny(boundArgs, ',') + '){ return binder.apply(this,arguments); }')(binder); |
| |
| if (target.prototype) { |
| var Empty = function Empty() {}; |
| Empty.prototype = target.prototype; |
| bound.prototype = new Empty(); |
| Empty.prototype = null; |
| } |
| |
| return bound; |
| }; |