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);

        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("你按下啦 shift,alt 或者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/>
    <br/>
    <input id="listenBtn" type="button" value="事件监听器"/>
    <br/>
    <div>
        <p id="content">广州新华学院</p>
        
        <button id="removeBtn">解除</button>
    </div>
    <br/> 
     <div>
        <p id="content1">信息科学学院</p>
        <button id="removeBtn1">解除</button>
    </div> 
</body>
</html>