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