Friday, November 13, 2015

How to be a software engineer 28

HTML Scripts


JavaScripts make HTML pages more dynamic and interactive.

Try it Yourself - Examples


How to insert a script into an HTML document.

How to handle browsers that do not support scripting, or have scripting disabled.

The HTML <script> Tag

The <script> tag is used to define a client-side script, such as a JavaScript.
The <script> element either contains scripting statements or it points to an external script file through the src attribute.
Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.
The script below writes Hello JavaScript! into an HTML element with id="demo":

Example

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>


The HTML <noscript> Tag

The <noscript> tag is used to provide an alternate content for users that have disabled scripts in their browser or have a browser that doesn't support client-side scripting.
The <noscript> element can contain all the elements that you can find inside the <body> element of a normal HTML page.
The content inside the <noscript> element will only be displayed if scripts are not supported, or are disabled in the user's browser:

Example

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>

<noscript>Sorry, your browser does not support JavaScript!</noscript>

A Taste of JavaScript (From Our JavaScript Tutorial)

Here are some examples of what JavaScript can do:

JavaScript can change HTML content:

document.getElementById("demo").innerHTML = "Hello JavaScript!";

JavaScript can change HTML styles:

document.getElementById("demo").style.fontSize = "25px";

JavaScript can change HTML attributes:

document.getElementById("image").src = "picture.gif";

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