JavaScript How To
The HTML <script> tag is used to insert a JavaScript into an HTML page.
Put a JavaScript into an HTML page
The example below shows how to use JavaSript to write text on a web page:
Example
<html>
<body>
<script type="text/javascript">
document.write("Hello World!");
</script>
</body>
</html>
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The example below shows how to add HTML tags to the JavaScript:
Example
<html>
<body>
<script type="text/javascript">
document.write("<h1>Hello World!</h1>");
</script>
</body>
</html>
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Example Explained
To insert a JavaScript into an HTML page, we use the <script> tag. Inside the <script> tag we
use the type attribute to define the scripting language.
So, the <script type="text/javascript"> and </script> tells where the JavaScript starts and ends:
<html>
<body>
<script type="text/javascript">
...
</script>
</body>
</html> |
The document.write command is a standard JavaScript command for writing output to a page.
By entering the document.write command between the <script> and </script> tags, the browser will recognize it as a JavaScript command and
execute the code line. In this case the browser will write Hello World! to the page:
<html>
<body>
<script type="text/javascript">
document.write("Hello World!");
</script>
</body>
</html> |
Note: If we had not entered the <script> tag, the browser would have
treated the document.write("Hello World!") command as pure text, and just write the entire line on the page.
Try it yourself
How to Handle Simple Browsers
Browsers that do not support JavaScript, will display JavaScript as page content.
To prevent them from doing this, and as a part of the JavaScript standard, the HTML comment tag should be used to "hide" the JavaScript.
Just add an HTML comment tag <!-- before the first JavaScript statement, and a --> (end of comment) after the last JavaScript statement, like this:
<html>
<body>
<script type="text/javascript">
<!--
document.write("Hello World!");
//-->
</script>
</body>
</html> |
The two forward slashes at the end of comment line (//) is the JavaScript comment symbol. This prevents JavaScript from executing the --> tag.
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