Is the \'type\' attribute in script tags really necessary in web scripting?

Understanding MIME Types in Web Scripting

While web servers generally set MIME types, the question remains: Is the "type" attribute in script tags redundant?

The Role of the "type" Attribute

According to Douglas Crockford, the "type" attribute is optional. Netscape 2 introduced JavaScript as the default scripting language for browsers, making the attribute unnecessary. In XHTML, it's required but superfluous, and in HTML, it's best omitted.

However, the W3C opted for a "type" attribute that specifies a MIME type. Unfortunately, this type is not standardized and varies among "text/javascript," "application/ecmascript," and others. Fortunately, browsers default to JavaScript, making the attribute superfluous.

Experimentation with Different MIME Types

To demonstrate, a series of scripts with different MIME types were tested:

<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, all scripts except those with type="baloney" ran successfully. IE8 failed to execute script 1 (type="application/ecmascript") and script 3.

Conclusion

Based on these limited tests, the "type" attribute appears to be largely unnecessary. However, if you choose to use it, be sure to specify a legal browser-dependent value. Ultimately, it's best practice to omit the attribute, as the browser will interpret the script correctly regardless.

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