console 命令行工具 X clear

console

function alertSecond(){
    alert("第2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);

    //解除按钮        
    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);
        //2
        
    var oPContent1=document.getElementById("content1");
    oPContent1.onclick=changeColor;

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

    oBtn1.addEventListener("click",function(){
        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>
    <input id="listenBtn" type="button" value="监听按钮"/>

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

        <button id="removeBtn">解除按钮</button>
    </div>
    <div>
        <p id="content1">广州新华学院</p>

        <button id="removeBtn1">解除按钮</button>
    </div>
</body>
</html>