bind改变this指向【与定时器一起使用】，绑定后不会立刻执行

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<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>Document</title>
</head><body><button>点击</button><button>点击</button><button>点击</button><button>点击</button><script>// 不会调用原来的函数// 返回新函数var btns = document.querySelectorAll('button')btns.forEach(function (value, index, array) {btns[index].onclick = function () {this.disabled = truesetTimeout(function () {// this.disabled = falsethis.disabled = false}.bind(this), 3000);}})</script>
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