bc518174
 王天杨
提交两个项目文件
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'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;
};
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