Do html5 data attributes need a value? [duplicate]

Answer 1

Simple Boolean Test For Element Attributes

To expand on Alohci's excellent answer, the following is a simple, flexible way to test for a true boolean attribute value supplied using one of three standard HTML conventions: , , or .

var a = elem['data-bar'];
var aTrue = ( a != null && a !== false && a !== 0 && a.charAt(0) != 'f' &&
              a.charAt(0) != 'n' );

With the code above, the value is false if undefined or set to one of: f*, n*, 0 (case-insensitive), and true if defined and set to one of: (empty string), (attribute name), (anything else).

Empty strings are evaluated to true here because HTML attributes without values are '' which equal false in JS (and something like should equal ). You can use the above code for more general string testing by removing != null && a !== false.