js 中什么是 softbind，如何实现
更多描述 相关问题:
Issue 欢迎在 Gtihub Issue 中回答此问题: Issue 33 (opens in a new tab)
Author 回答者: newwangyiyang (opens in a new tab)
bind函数多次调用会已第一次绑定的this为准，softbind已最后一次绑定传入的this为准；
Author 回答者: miaooow (opens in a new tab)
Function.prototype.softBind = function(obj, ...rest) {
const fn = this
const bound = function(...args) {
const o = !this || this === (window || global) ? obj : this
return fn.apply(o, [...rest, ...args])
}
bound.prototype = Object.create(fn.prototype)
return bound
}function foo() {
console.log(name: ${this.name});
}
let obj = {name: "obj"};
obj2 = {name: "obj2"};
obj3 = {name: "obj3"};
let fooBJ = foo.softBind(obj);
fooBJ(); // name: obj 这个时候软绑定已经生效了，this绑定到obj上
obj2.foo = foo.softBind(obj);
obj2.foo(); //name: obj2 这里已经的this隐式绑定到obj2上了
fooBJ.call(obj3); // name: obj3 这里this被硬绑定到obj3上了
setTimeout(obj2.foo, 100); // name: obj 软绑定了最初的objAuthor 回答者: shfshanyue (opens in a new tab)
TODO
Author 回答者: shuangcherry (opens in a new tab)
bound.prototype = Object.create(fn.prototype); 为什么要有这一句，不是很懂
Author 回答者: shen076 (opens in a new tab)
Function.prototype.softBind = function (obj, ...args) {
const fn = this;
return function (...args2) {
return fn.apply(this === global ? obj : this, args.concat(args2));
};
};Author 回答者: zhangtuo1999 (opens in a new tab)
Function.prototype.softBind = function (ctx) {
ctx ??= globalThis;
ctx = Object(ctx);
const self = this;
const args = [...arguments].slice(1);
function bound() {
fn.call(new.target || this !== globalThis ? this : ctx, ...args);
}
bound.prototype = self.prototype;
return bound;
};Author 回答者: rujptw (opens in a new tab)
bound.prototype = Object.create(fn.prototype); 为什么要有这一句，不是很懂 是要考虑到new的情况来着
Author 回答者: Yeti-xxx (opens in a new tab)
实现一个Bind:
function person(a, b, c, d, e) {
console.log(this.name, a + b + c);
console.log(d,e);
}
const yeti = {
name: 'yeti'
}
// 实现一个bind
Function.prototype.newmyBind = function (obj, ...args) {
const that = this
return function (...rest) { //返回一个修改好this的函数
// ...rest来自返回函数传入的参数 ...args是调用Bind时传入的参数
that.call(obj, ...args, ...rest)
}
}
const resBind = person.newmyBind(yeti, 1, 2, 6) //1 2 6 就是...args
resBind(5, 6) //传入...rest