console 命令行工具 X clear

console

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

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

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

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

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

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

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

function alertThird() {
    alert("第3次");
}
oListenBtn.addEventListener("click", alertThird, false);

oListenBtn.removeEventListener("click", alertSecond, false);

var oPContent=document.getElementById("content");
oPContent.addEventListener("click",changeColor,false);
oPContent.addEventListener("click",changeBackgroundColor,false);

var oRemoveBtn=document.getElementById("removeBtn");
oRemoveBtn.addEventListener("click",function(event){
    console.log(event.type);
    oPContent.removeEventListener("click",changeColor,false);

},false);

var oPContent1=document.getElementById("content1");
oPContent1.onclick=function(){
    if(this.style.color="red"){
        this.style.color="black";
    }
    else{
        this.style.color="red";
    }
    if(this.style.backgroundColor=="lightskyblue"){
        this.style.backgroundColor="white";
    }
    else{
        this.style.backgroundColor="lightskyblue";
    }
}

var oRemoveBtn1=document.getElementById("removeBtn1");
oRemoveBtn1.addEventListener("click",function(){
    oPContent1.oclick=changeBackgroundColor;
},false);

document.addEventListener("keydown", function(event){
        console.log(event.type);
        console.log("你按下 " + event.keyCode);
        if (event.altKey) {
            console.log("你按下了Alt");
        }
        if (event.ctrlKey) {
            console.log("你按下了Ctrl");
        }
        if (event.shiftKey) {
            console.log("你按下了Shift");
        }
    }, false)

    document.addEventListener("keyup", function(event){
        console.log(event.type);
        console.log("你松开 " + event.keyCode);
        if (event.altKey) {
            console.log("你松开了Alt");
        }
        if (event.ctrlKey) {
            console.log("你松开了Ctrl");
        }
        if (event.shiftKey) {
            console.log("你松开了Shift");
        }
    }, 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>

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

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