<!DOCTYPE html>

<head>

<title>Document</title>

</head>

<body>

<button id="btn1">添加监听事件</button>

<button id="btn2">移除监听事件</button>

document.getElementById('btn1').addEventListener("click", fn3)

document.getElementById('btn2').onclick = function () {

document.getElementById('box3').removeEventListener("click", fn3)

}

function fn3() {

document.getElementById('box3').onclick = function () {

alert(11111)

}

}

</script>

</body>

</html>

大佬救命，keil4刚安装，一点开就弹出这个