Do we need to have DOCTYPE Declaration of html5 for data-attribute in Jquery

Is this really needed when we data-attr for the elements in html

<input type ="text"开发者_如何学JAVA name="text1" id ="text1" data-attr="<?php echo $hell ?>">

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Is it needed? no. Will it pass the W3C validator without it? no.

You'll have no actual issues using data attributes either way, it just depends how important validation is to you.

• Without HTML5 DOCTYPE: It'll work, the validator will fail with an HTML4 doctype.
• With HTML5 DOCTYPE: It'll work and be valid.

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No. You don't need to write your code any particular way.

You should provide the correct doctype for the content. If you'd like to add data elements/attributes in HTML4 and below, you can namespace your elements and attributes (mydata:attr="...").