console 命令行工具 X clear

console

function alertSecond() {
    alert("第2次");
}
window.onload = function () 
{
    var oBtn = document.getElementById("btn");
    oBtn.onclick = function () {
        alert("第1次");
    };
    oBtn.onclick = function () {
        alert("第2次");
    };

    oBtn.onclick = function () {
        alert("第1次");
        alert("第2次");
        alert("第3次");
    };

     var oBtn = document.getElementById("listenBtn");

     oBtn.addEventListener("click", function(){
         alert("第1次");
     }, false);
     oBtn.addEventListener("click", alertSecond, false);
     oBtn.removeEventListener("click", alertSecond, false);

}

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
      
    </script>
</head>
<body>
    <input id="btn" type="button" value="按钮"/>
    <br/>
    <br/>
    <input id="listenBtn" type="button" value="监听按钮"/>
    <div>
        <p id="content">广州新华学院</p>

        <button id="removeBtn">解除</button>
    </div>
</body>
</html>