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abhidilliwal/querySelectorPerf.js

Last active February 29, 2016 09:44
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  1. abhidilliwal revised this gist Feb 29, 2016. No changes.
  2. abhidilliwal created this gist Feb 29, 2016.
    19 changes: 19 additions & 0 deletions querySelectorPerf.js
    View file
    Original file line number Diff line number Diff line change
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    // source/credits: https://github.com/madrobby/zepto/blob/master/src/zepto.js

    // usage query(document.body, '.cls .childrens')
    function query(element, selector){
    var found,
    maybeID = selector[0] == '#',
    maybeClass = !maybeID && selector[0] == '.',
    nameOnly = maybeID || maybeClass ? selector.slice(1) : selector, // Ensure that a 1 char tag name still gets checked
    isSimple = /^[\w-]*$/.test(nameOnly);
    return (element.getElementById && isSimple && maybeID) ? // Safari DocumentFragment doesn't have getElementById
    ( (found = element.getElementById(nameOnly)) ? [found] : [] ) :
    (element.nodeType !== 1 && element.nodeType !== 9 && element.nodeType !== 11) ? [] :
    [].slice.call(
    isSimple && !maybeID && element.getElementsByClassName ? // DocumentFragment doesn't have getElementsByClassName/TagName
    maybeClass ? element.getElementsByClassName(nameOnly) : // If it's simple, it could be a class
    element.getElementsByTagName(selector) : // Or a tag
    element.querySelectorAll(selector) // Or it's not simple, and we need to query all
    );
    }