【Q031】js 中如何实现 bind #32
Comments
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最简单的 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) |
|
那我再抄一个加强版吧嘻嘻 |
This was referenced Jul 30, 2021
Function.prototype.fakeBind = function (target, ...args) {
return (...rest) => this.apply(target, args.concat(rest).slice(0, this.length));
}; |
|
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;
}; |
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
} |
Function.prototype._bind(obj,...args){
obj.fn = this
return function(...args){
const r = obj.fn(...args)
delete obj.fn
return r
}
} |
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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])类似功能相关问题:
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