Is the \'type\' Attribute in JavaScript and CSS Scripts Really Necessary?

Why Specify the 'type' Attribute in JavaScript or CSS Scripts?

Although web servers determine MIME types, the question arises: why do we include the 'type="text/javascript"' or 'type="text/css"' attribute in HTML scripts? Isn't this attribute redundant and ignored?

Answer

According to Douglas Crockford:

• The 'type="text/javascript"' attribute is optional. Since Netscape 2, JavaScript has been the default programming language in browsers. In XHTML, this attribute is required but unnecessary, while in HTML, it's best to omit it.
• W3C introduced a 'type' attribute that accepts a MIME type but did not standardize it, leading to variations like "text/javascript" and "application/ecmascript." However, browsers will always default to JavaScript as the programming language.

For demonstration purposes, five scripts with different 'type' attributes were tested in Chrome and IE8:

<script type="application/ecmascript">alert("1");</script>
<script type="text/javascript">alert("2");</script>
<script type="baloney">alert("3");</script>
<script type="">alert("4");</script>
<script>alert("5");</script>

In Chrome, scripts 1-4 worked, while script 3 (type="baloney") failed. In IE8, scripts 1 and 3 failed to execute.

Based on this small sample, it appears that the 'type' attribute can be safely ignored. However, if used, it should conform to legal values supported by the browser.

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