js 中如何实现 bind
更多描述 提供以下测试用例，注意第二条测试用例，因此 bind 可实现
_.partial(func, [partials])类似功能
function f(b) {
console.log(this.a, b);
}
//=> 3, 4
f.fakeBind({ a: 3 })(4);
//=> 3, 10
f.fakeBind({ a: 3 }, 10)(11);相关问题:
- 【Q032】js 中什么是 softbind，如何实现 (opens in a new tab)
- 【Q656】JS 中如何实现 call/apply (代码集合) (opens in a new tab)
Issue 欢迎在 Gtihub Issue 中回答此问题: Issue 32 (opens in a new tab)
Author 回答者: shfshanyue (opens in a new tab)
最简单的 bind 一行就可以实现，而在实际面试过程中也不会考察你太多的边界条件
Function.prototype.fakeBind = function (obj, ...args) {
return (...rest) => this.call(obj, ...args, ...rest);
};测试一下
function f(arg) {
console.log(this.a, arg);
}
// output: 3, 4
f.bind({ a: 3 })(4);
// output: 3, 4
f.fakeBind({ a: 3 })(4);Author 回答者: SageSanyue (opens in a new tab)
那我再抄一个加强版吧嘻嘻 《JavaScript权威指南》P191 ES3实现bind
if (!Function.prototype.bind) {
Function.prototype.bind = function(o /*, args */) {
var self = this, boundArgs = arguments;
return function () {
var i, args = [];
for (i = 1; i < boundArgs.length; i++) {
args.push(boundArgs[i])
}
for (i = 0; i < arguments.length; i++) {
args.push(arguments[i])
}
return self.apply(o, args)
}
}
}Author 回答者: Vi-jay (opens in a new tab)
Function.prototype.fakeBind = function (target, ...args) {
return (...rest) =>
this.apply(target, args.concat(rest).slice(0, this.length));
};Author 回答者: hefeng6500 (opens in a new tab)
bind 优化版本：考虑 bind 后返回的函数作为构造函数被 new
Function.prototype.bind = function (context, ...args) {
const self = this;
const fn = function (...newArgs) {
self.apply(this instanceof fn ? this : context, args.concat(newArgs));
};
fn.prototype = Object.create(this.prototype);
return fn;
};Author 回答者: zhangtuo1999 (opens in a new tab)
Function.prototype.myBind = function (ctx) {
ctx ??= globalThis;
ctx = Object(ctx);
const self = this;
const args = [...arguments].slice(1);
function bound() {
self.call(new.target ? this : ctx, ...args);
}
bound.prototype = self.prototype;
return bound;
};Author 回答者: Yinzhuo19970516 (opens in a new tab)
Function.prototype._bind(obj,...args){
obj.fn = this
return function(...args){
const r = obj.fn(...args)
delete obj.fn
return r
}
}