bind()
- 参数的合并
- 原型继承需要一个中间过度函数
- this 的 判断
this instanceof temp ? this : oThis
有些判断是 this instanceof temp && oThis ? this : oThis || window 不是很懂
bind() -- mdn
Function.prototype.mybind = function(oThis){
var self = this;
var args = Array.prototype.slice.call(arguments,1);
var temp = function(){};
var result = function(){
return self.apply(this instanceof temp
? this
: oThis ,args.concat(Array.prototype.slice.call(arguments)));
}
temp.prototype = self.prototype;
result.prototype = new temp();
return result;
}
function A(name,age){
this.name = name;
this.age = age;
}
var B = A.mybind(null,'bby365');
var b1 = new B(18);
call()
Function.prototype._call = function (context) {
var context = context || window;
var args = [];
for (var i = 1; i < arguments.length; i++) {
args.push(arguments[i]);
}
context.fn = this;
var res = context.fn(...args);
delete context.fn;
return res;
}
// es6
Function.prototype._call = function (context,...args) {
var context = context || window;
context.fn = this;
var res = context.fn(...args);
delete context.fn;
return res;
}
apply()
Function.prototype._apply = function(context,arr){
var context = context || window;
context.fn = this;
var res = context.fn(...arr);
delete context.fn;
return res;
}
// 例子
function add(c, d){
return this.a + this.b + c + d
}
var o = {a:1, b:3}
add.apply(o, [5, 7]) // 16
总结：call() 和 apply() 返回的是执行的结果，而bind() 返回的是一个新的函数。
