What is the best way to include JavaScript file using script tag?

Question

I generally include JavaScript files using the script tag as below.

<script type="text/javascript" src="somefile.js"></script>

I have seen some people using the language attribute as well.

Now-a-days I find many people omitting the type attribute. I have started to get a feeling that if JavaScript is the default scripting language then even I should omit the type attribute. Would it be good to omit the type attribute? Would it cause any problems?

Answer 1

Take a look at this as a reference (Book of Speed): http://www.bookofspeed.com/chapter3.html

Essentially the best way is to combine all your javascript into one file called something like all.min.js that is also minimized.

Typically in HTML5 you would do something like:

<script src="js/all.min.js"></script>

As you can see, you DO NOT need the type attribute in HTML5, but you do in other versions of HTML and XHTML (http://dev.w3.org/html5/spec-author-view/the-script-element.html). The spec clarifies that if the content is other than "text/javascript" then you need to specify the type attribute, in HTML5.

Some things to remember:

• Always include it before the closing tag. (http://www.yuiblog.com/blog/2008/07/22/non-blocking-scripts/)
• You should load your scripts in a non-blocking pattern (http://labjs.com/)

Note:

If you are going to specify another type other than "text/javascript" you would use one of the following:

• "application/ecmascript"
• "application/javascript"
• "application/x-ecmascript"
• "application/x-javascript"
• "text/ecmascript" "text/javascript"
• "text/javascript1.0"
• "text/javascript1.1"
• "text/javascript1.2"
• "text/javascript1.3"
• "text/javascript1.4"
• "text/javascript1.5"
• "text/jscript"
• "text/livescript"
• "text/x-ecmascript"
• "text/x-javascript"
• "text/javascript;e4x=1"

The above list is from: http://dev.w3.org/html5/spec-author-view/the-script-element.html#scriptingLanguages

Remember that you would not use the language attribute, only the type attribute.

Answer 2

Just take a look at the w3school. The type attribute is required! Some browser might also treat the scripts based on its extension or mime-type, but I strongly recommend to comply with standards.