Question

function xmlParser(xml, projectName) {

var currentIndex = 0;

$(xml).find('entry').each(function(){

    if($(this).attr('projectName').toLowerCase() == projectName) {

        $previous = $(xml).find('entry')[currentIndex - 1]);
        $project = $(this);
        $next = $(xml).find('entry')[currentIndex + 1]);

        //do something with these objects..

    }
    currentIndex++;

});
}

Here is some sample code. I have an XML file full of ‘entry’ elements. Each element has a ‘projectName’ attribute.

The code basically scans the XML for a project name, like say “Magic Giraffes”, returns the XML element matching it, and also the previous & next projects. It works… but I want to know if it’s the most efficient way to do it.

See how I’m handling the $previous and $next parts? It’s calling the .find() function two more times, and then grabbing elements based on the (-1) and (+1) of the current index. Is there a more efficient way to do this?

Answer 1

assuming that each “entry” are siblings, without other elements inbetween:

$project = $(this);
$previous = $project.prev();
$next = $project.next();

else

$project = $(this);
$previous = $project.prev('entry');
$next = $project.next('entry');

in order to completly “optimize” your code, you can use variable as often as you can:

function xmlParser(xml, projectName) {

var exp = new regexp(projectName, "gi"); 
var $entries = $('entry', xml).filter(function() {
    return exp.test( $(this).attr('projectName'));
});

$entries.each(function(){
    $project = $(this);
    $previous = $this.prev();
    $next = $this.next();

    //do something with these objects..

    });    
}

here the “$entries” variable prevent useless access to the full document, “$this” some parsing/selecting by jquery(but that effect is limited on performance).

edit: I did change the looping / matching method, with the help of the “filter” method. Note: if you are certain there is only one “projectname” in entries, you can get rid of the the “$.each” layer, as then “$entries” becomes “$project” directly