CODEWITHSUNDEEP
jquery
Jon
Jon

Reputation: 8541

What does this jQuery line do?

I have a line of jQuery code that is causing an error as I placed two periods in front of the b class. I am wondering how does jQuery interpret the following line? If I had only one period in front of b instead of two, I assume that jQuery interpret it as: "if class b exists within class a which exists in the parent of this, alert prompt hi".

if ( $(this).parent().find(".a ..b") ) {
  alert("hi");
});

Upvotes: -1

Views: 115

Answers (2)

Guffa
Guffa

Reputation: 700830

That might depend on the browser. Both in Internet Explorer 9 and Firefox 10.0, the selector will just find nothing, and you get back an empty jQuery object.

As you are using the jQuery object as the condition in the if, the code inside the if will always run. A jQuery object is always a non-falsy value, so the condition will always be evaluated as true, regardless of whether jQuery found anything from your selector.

If you want to check if something was found, use the length property:

if ( $(this).parent().find(selector).length ) {

Upvotes: 3

Darin Dimitrov
Darin Dimitrov

Reputation: 1039488

.a ..b is an invalid selector and it will throw error:

Uncaught Error: Syntax error, unrecognized expression: .

.a .b is the correct selector.

So $(this).parent().find(".a .b") will first fetch the direct parent node of this, then it will search for a descendant element with the class="a" and then another descendant element within with the class="b", and if it finds it will alert hi.

Upvotes: 8

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