Javascript return not breaking out of function

Question

I have a javascript function which checks to see if an artist exists in an XML file:

function artistExists(artist) {
// get data from artists.xml 
$('.loading').show();
$.get(artists_xml, function(xml){  
    $('.loading').hide();
    $(xml).find('artist').each(function(){
        if ($(this).find("ar_artist").text() == artist.val()) {
            alert ('artist exists');
            return true;
        } //end if
    });  // end each
    alert ('artist does not exist');
    return false;
}); // end .get function
} // end of artistExists function

Am I right in thinking that the 'return true' line should quit execution of the function? I thought it would, but after finding a record and running the first alert execution continues to the failure alert at the bottom.

What am I doing wrong please? Thank you.

Answer 1

Yes, it does "quit" execution of the function. The question is, "which function?" In this case the answer should be pretty clear: it's the function passed to .each().

You can terminate the looping behavior of .each() by returning false instead of true, but that still won't get you out of the outer function. What you should probably consider is to set up a local variable in the outer function, and have the inner function set that when it finds something (and then break the .each() loop). Then the main function can check the local variable to see if it was set.

This is a case where I'd really like to use a .reduce() or .inject() API, but jQuery doesn't have one and they're really opposed to it.

Answer 2

Return false, rather than true, to terminate the each loop; from the docs:

We can stop the loop from within the callback function by returning false.

That will just terminate your each loop, though, not the overall function. You'll need to set a flag so you know whether you found something, e.g. something like this:

function artistExists(artist) {
// get data from artists.xml 
$('.loading').show();
$.get(artists_xml, function(xml){  
    var found = false;    // <== Added
    $('.loading').hide();
    $(xml).find('artist').each(function(){
        if ($(this).find("ar_artist").text() == artist.val()) {
            alert ('artist exists');
            found = true; // <== Added
            return false; // <== Modified
        } //end if
    });  // end each
    if (!found) {         // <== Added
        alert ('artist does not exist');
    }                     // <== Added
    return found;         // <== Modified
}); // end .get function
} // end of artistExists function