console 命令行工具 X clear

console

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3次");
            };
        } 



function changeColor() {
    if (this.style.color == "red") {
        this.style.color = "black";
    }
    else {
         this.style.color = "red";
    }
   
}

function changeBackgroundColor() {
    if (this.style.backgroundColor == "lightskyblue") {
        this.style.backgroundColor = "white";
    }
    else {
         this.style.backgroundColor = "lightskyblue";
    }
   
} 


oBtn.addEventListener("click",function(){
    alert("第一次");

},false);


var oBtn = document.getElementById("btn")

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
      
    </script>
</head>
<body>
    <input id="btn" type="button" value="按钮"/>


<div>
        <p id="content">广州新华学院</p>

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




    <div>
        <p id="content1">信息科学学院</p>

        <button id="removeBtn1">解除</button>
    </div> 



</body>
</html>