53 lines
1.4 KiB
JavaScript
53 lines
1.4 KiB
JavaScript
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'use strict';
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/* eslint no-invalid-this: 1 */
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var ERROR_MESSAGE = 'Function.prototype.bind called on incompatible ';
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var slice = Array.prototype.slice;
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var toStr = Object.prototype.toString;
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var funcType = '[object Function]';
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module.exports = function bind(that) {
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var target = this;
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if (typeof target !== 'function' || toStr.call(target) !== funcType) {
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throw new TypeError(ERROR_MESSAGE + target);
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}
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var args = slice.call(arguments, 1);
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var bound;
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var binder = function () {
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if (this instanceof bound) {
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var result = target.apply(
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this,
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args.concat(slice.call(arguments))
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);
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if (Object(result) === result) {
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return result;
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}
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return this;
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} else {
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return target.apply(
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that,
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args.concat(slice.call(arguments))
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);
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}
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};
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var boundLength = Math.max(0, target.length - args.length);
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var boundArgs = [];
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for (var i = 0; i < boundLength; i++) {
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boundArgs.push('$' + i);
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}
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bound = Function('binder', 'return function (' + boundArgs.join(',') + '){ return binder.apply(this,arguments); }')(binder);
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if (target.prototype) {
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var Empty = function Empty() {};
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Empty.prototype = target.prototype;
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bound.prototype = new Empty();
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Empty.prototype = null;
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}
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return bound;
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};
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