CODEWITHSUNDEEP
javascriptjqueryperformance
Thirk
Thirk

Reputation: 593

Why does this loop get progressively slower?

for (i = 0; i < $('body > p font i').length; i++) {
    current = [$('body > p font i').eq(index), $('body > p font i').eq(index).index('body > p font u, body > p font i')];
    getState(current[1]);
}

function getState(index) {
    // Lookup the object's index, then crawl up until you find a match
    while ($('body > p font u, body > p font i').eq(--index).filter('u').length == 0);
    console.log($('body > p font u, body > p font i').eq(index).text());
}

Fairly simple question. I'm iterating a jQuery result set against a selector filter until I find a match, climbing up through the result set as I go.

The longer this loop runs, the slower it becomes, almost exponentially so.

Upvotes: 4

Views: 134

Answers (1)

kidwon
kidwon

Reputation: 4504

You are seraching in the DOM tree on each iteration which is an expensive operation, the solution is cache:

var nodes = $('body > p font i');
for (var i = 0, size = nodes.length; i < size; i++) {
    current = [nodes.eq(index),nodes.eq(index).index('body > p font u, body > p font i')];
}

Upvotes: 2

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