javascript: what can javascript do?

1、Javascript can change html content

<!DOCTYPE html>
<html>
<body>

<h2>What Can JavaScript Do?</h2>

<p id="demo">JavaScript can change HTML content.</p>

<button type="button" onclick='document.getElementById("demo").innerHTML = "Hello JavaScript!"'>Click Me!</button>

</body>
</html>

2、Javascript can change html attributes

<!DOCTYPE html>
<html>
<body>

<h2>What Can JavaScript Do?</h2>

<p>JavaScript can change HTML attribute values.</p>

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

<button onclick="document.getElementById('myImage').src='pic_bulbon.gif'">Turn on the light</button>

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

<button onclick="document.getElementById('myImage').src='pic_bulboff.gif'">Turn off the light</button>

</body>
</html>

3、Javascript can change CSS style

<!DOCTYPE html>
<html>
<body>

<h2>What Can JavaScript Do?</h2>

<p id="demo">JavaScript can change the style of an HTML element.</p>

<button type="button" onclick="document.getElementById('demo').style.fontSize='35px'">Click Me change Size!</button>


<button type="button" onclick="document.getElementById('demo').style.backgroundColor='yellow'">Click Me change color!</button>

</body>
</html>

4、Javascript can change hide show html

<!DOCTYPE html>
<html>
<body>

<h2>What Can JavaScript Do?</h2>

<p>JavaScript can show hidden HTML elements.</p>

<p id="demo" style="display:none">Hello JavaScript!</p>
<p id="demo1" style="display:block">Hello JavaScript 001!</p>

<button type="button" onclick="document.getElementById('demo').style.display='block'">Click Me to show!</button>


<button type="button" onclick="document.getElementById('demo1').style.display='none'">Click Me to hide!</button>

</body>
</html>