Why does $(‘#id’) return true if id doesn’t exist?

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This behaviour was chosen because otherwise jQuery would regularly throw NullReference Exceptions

Almost all jQuery functions return a jQuery object as a wrapper around the Dom elements in question, so you can use dot notation.

$("#balloon").css({"color":"red"});

Now imagine $("#balloon") returned null. That means that $("#balloon").css({"color":"red"});
would throw an error, rather than silently doing nothing as you would expect.

Hence, you just gotta use .length or .size().

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