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<html> <head> <script type="text/javascript" src="jquery.js"></script> </head> <body> <ul> <li><strong>list</strong> item 1 - one strong tag</li> <li><strong>list</strong> item <strong>2</strong> - two <span>strong tags</span></li> <li>list item 3</li> <li>list item 4</li> <li>list item 5</li> <li>list item 6</li> </ul> <script type="text/javascript"> $('li').filter(function(index) { return $('strong', this).length == 1; }).css('background-color','red'); </script> </body> </html> Given the HTML above, what's the meaning of the comma in the selector below?
return $('strong', this).length == 2; What will happen if I remove the word 'strong'?
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The comma in a CSS selector separates multiple selectors within the same styles. For example, let's look at some CSS below. With this syntax, you are saying that you want th tags, td tags, paragraph tags with the class red, and the div tag with the ID firstred all to have the style color red.
jQuery selectors allow you to select and manipulate HTML element(s). jQuery selectors are used to "find" (or select) HTML elements based on their name, id, classes, types, attributes, values of attributes and much more. It's based on the existing CSS Selectors, and in addition, it has some own custom selectors.
It sets this as the context from which the query is performed.
An equivalent (and slightly more efficient) way to write it is:
return $(this).find('strong').length == 2; When I say equivalent, I mean behind the scenes, it is actually flipped around into the version above.
If you remove the 'strong', you won't have a valid selector. You'll be doing:
return $(this).find('').length == 2; Looks like it just returns an empty jQuery object, which means length will be 0, so you won't get any elements out of the .filter().
Reference:
http://api.jquery.com/jQuery/
jQuery( selector [, context ] )
context
Type: Element or jQuery
A DOM Element, Document, or jQuery to use as context
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