Question

I’m using following line and I would like to make it case-insensitive:

var matches = $(this).find('div > span > div#id_to_find[attributeName ^= "filter"]');
if (matches.length > 0) {
}

My question is that how can I make the selector ^= to be case-insensitive? Maybe changing to filter and then some regexp?

Answer 1

To do a case-insensitive attribute selection, you need to write a custom selector function.

$.expr[':'].iAttrStart = function(obj, params, meta, stack) {
    var opts = meta[3].match(/(.*)\s*,\s*(.*)/);
    return (opts[1] in obj) && (obj[opts[1]].toLowerCase().indexOf(opts[2].toLowerCase()) === 0);
};

You can use this like this:

$('input:iAttrStart(type, r)')

This will match any input elements whose type attribute begins with R or r (so it would match RADIO, radio, RESET or reset). This is a pretty silly example, but it should do what you need.

---

Re the comment that the function is hard to understand, I’ll explain it a little.

$.expr[':'].iAttrStart = function(obj, params, meta, stack) {

This is the standard signature for creating custom selectors.

var opts = meta[3].match(/(.*)\s*,\s*(.*)/);

meta is an array of details about the call. meta[3] is the string passed as the parameter. In my example, this is type, r. The regex matches type and r separately.

return (opts[1] in obj) && (obj[opts[1]].toLowerCase().indexOf(opts[2].toLowerCase()) === 0);

Return if both these are true:

1. The requested attribute exists on this object (opts[1] in obj)
2. The search term (changed to lower-case) is found at the very beginning of the element’s attribute value, also changed to lower case.

I could have made this easier to read using jQuery syntax rather than native JS syntax, but that would have meant reduced performance.