console 命令行工具 X clear

console

function alertSecond(){
    alert("第二次");
}
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";
    }
   
} 

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

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

        oBtn.addEventListener("click",alertSecond,false);
        oBtn.removeEventListener("click",alertSecond,false);
        
        var oPContent = document.getElementById("content");

        oPContent.addEventListener("click",changeColor,false);
        oPContent.addEventListener("click",changeBackgroundColor,false);

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

        oBtn.addEventListener("click",function(){
            oPContent.removeEventListener("click",changeColor,false);
        },false);

        var oPContent1 = document.getElementById("content1");

        oPContent1.onclick=changeColor;

        var oBtn1= document.getElementById("removeBtn1");

        oBtn1.addEventListener("click",function(event){
            alert(event.type);
            oPContent1.onclick=null;
        },false);

        document.addEventListener("keydown",function(event){
            console.log(event.type)
            if(event.shiftKey||event.altKey||event.ctrlKey){
                console.log("你按下了shift,alt或ctrl");
            }
            console.log("你按下啦"+event.keyCode);
        });

        document.addEventListener("keyup",function(event){
            console.log(event.type);
            console.log("你松开啦"+event.keyCode);
        })
}

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
      
    </script>
</head>
<body>
    <input id="btn" type="button" value="按钮"/>
    <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> 
    <div>
        <p id="content1">信息科学学院</p>

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

</body>
</html>