更改 JavaScript 中按钮的功能

Question

我正在 W3School 上练习 JS，在尝试 "The Light Bulb" 练习时我想更改两个按钮的功能！

我想做的是添加另一个按钮，单击该按钮将互换标签 "Turn On the Light" 和 "Turn off the Light" 以及 onclick 操作。

<!DOCTYPE html>
<html>
<body>

<h1>What Can JavaScript Do?</h1>

<p><b><i>JavaScript can change HTML attributes.</i></b></p>

<p>In this case JavaScript changes the src (source) attribute of an image.</p>

<!-- Button1 (LHS) -->
<button id="buttonId1" onclick="document.getElementById('myImage').src='pic_bulboff.gif'">Turn off the light</button>

<!-- Image of the Bulb -->
<img id="myImage" src="pic_bulbon.gif" style="width:100px">

<!-- Button2 (RHS) -->
<button id="buttonId2" onclick="document.getElementById('myImage').src='pic_bulbon.gif'">Turn on the light</button>

<!-- Function to interchange label of both buttons along with the onclick actions -->
<script>
function clickButton() {
    <!-- initially button1 is for switching off the button, changing it to turn-on state -->
    document.getElementById('buttonId1').innerHTML = 'Turn on the light';
    document.getElementById('buttonId1').onclick="document.getElementById('myImage').src='pic_bulbon.gif' " ; 

    <!-- initially button2 is for switching on the button, changing it to turn-off state -->
    document.getElementById('buttonId2').innerHTML = 'Turn off the Light';
    document.getElementById('buttonId2').onclick="document.getElementById('myImage').src='pic_bulboff.gif' " ; 
}
</script>


<br>
<!-- Adding new button  to manipulate button functionality -->
<button onclick="clickButton()" >Do Not Click Me</button>
</body>
</html>

我尝试执行上面的代码，它替换了单击 "Do Not Click Me" 按钮时的标签，但没有更改 onclick 操作！

我需要帮助来实现该功能。

Answer 1

改用这个。 . .

document.getElementById('buttonId1').onclick = function() { 
    document.getElementById('myImage').src='pic_bulbon.gif';
};
document.getElementById('buttonId2').onclick= function() { 
    document.getElementById('myImage').src='pic_bulboff.gif'
};

Answer 2

试试这个：

<!DOCTYPE html>
<html>
<head>

<script type="text/javascript">
function onBulb(){
   document.getElementById('myImage').src='pic_bulbon.gif';
}

function offBulb(){
   document.getElementById('myImage').src='pic_bulboff.gif';
}
function swapButtons(){
   document.getElementById('buttonId1').innerText="Turn off the light";
   document.getElementById('buttonId1').onclick=offBulb;
   document.getElementById('buttonId2').innerText="Turn on the light";
   document.getElementById('buttonId2').onclick=onBulb;
}
</script>

</head>
<body>

<h1>What Can JavaScript Do?</h1>

<p>JavaScript can change HTML attributes.</p>

<p>In this case JavaScript changes the src (source) attribute of an image.</p>


<button id="buttonId1" onclick="onBulb()">Turn on the light</button>

<img id="myImage" src="pic_bulboff.gif" style="width:100px">

<button id="buttonId2" onclick="offBulb()">Turn off the light</button>

<button onclick="swapButtons()" >Swap Buttons</button>


</body>
</html>

Answer 3

onclick 必须设置为一个函数，而不是字符串..

function clickButton() {
    document.getElementById('buttonId1').innerHTML = 'Turn on the light';
    document.getElementById('buttonId1').onclick= function () {functionSwitch(true)}
    document.getElementById('buttonId2').innerHTML = 'Turn off the Light';
    document.getElementById('buttonId2').onclick= function() {functionSwitch(false)}
}

function functionSwitch(state) {
 
    if(state == false)
        document.getElementById('myImage').src='https://openclipart.org/image/2400px/svg_to_png/119749/power-off.png';
    else
        document.getElementById('myImage').src='http://icons.iconarchive.com/icons/paomedia/small-n-flat/1024/sign-check-icon.png';
}

<body>

  <h1>What Can JavaScript Do?</h1>

  <p><b><i>JavaScript can change HTML attributes.</i></b>
  </p>

  <p>In this case JavaScript changes the src (source) attribute of an image.</p>

  <!-- Button1 (LHS) -->
  <button id="buttonId1" onclick='functionSwitch(false)'>Turn off the light</button>

  <!-- Image of the Bulb -->
  <img id="myImage" src="http://icons.iconarchive.com/icons/paomedia/small-n-flat/1024/sign-check-icon.png" style="width:100px">

  <!-- Button2 (RHS) -->
  <button id="buttonId2" onclick='functionSwitch(true)'>Turn on the light</button>

  <br>
  <!-- Adding new button  to manipulate button functionality -->
  <button onclick="clickButton()">Do Not Click Me</button>
</body>

更改 JavaScript 中按钮的功能

Changing the Functionality of Button in JavaScript

javascript

buttonclick