Run results for: querySelectorAll vs query vs qs

100 Li elements using querySelectorAll and custom query function got from http://ryanmorr.com/abstract-away-the-performance-faults-of-queryselectorall/ and qs from https://codereview.stackexchange.com/questions/25452/very-fast-query-selector

Run details:

User agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.89 Safari/537.36

Browser: Chrome 62

Operating system: Windows 8.1

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
query	37840.3 Ops/sec
querySelectorAll	21567.9 Ops/sec
getElementByTagName	3195101.5 Ops/sec
qs	2381009.5 Ops/sec

HTML Preparation code:

<html>
<body>
    <ul style="list-style: none outside none;">
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      <li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      	<li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      	<li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 2</li>
        <li style="float: left;display: block;width: 100px;height: 40px;">Field 3</li>
      	<li style="float: left;display: block;width: 100px;height: 40px;">Field 1</li>
    </ul>
</body>
</html>

Script Preparation code:

function query(selector, context) {
    context = context || document;
    // Redirect simple selectors to the more performant function
    if (/^(#?[\w-]+|\.[\w-.]+)$/.test(selector)) {
        switch (selector.charAt(0)) {
            case '#':
                // Handle ID-based selectors
                return [context.getElementById(selector.substr(1))];
            case '.':
                // Handle class-based selectors
                // Query by multiple classes by converting the selector 
                // string into single spaced class names
                var classes = selector.substr(1).replace(/\./g, ' ');
                return [].slice.call(context.getElementsByClassName(classes));
            default:
                // Handle tag-based selectors
                return [].slice.call(context.getElementsByTagName(selector));
        }
    }
    // Default to `querySelectorAll`
    return [].slice.call(context.querySelectorAll(selector));
}

/**

    A simple, fast query selector.

    @fileOverview 

*/
/**

Perform a simple query selection.

@param {String} query

@param {Node} root 
    Optional root node, defaults to qs.global.document. 

@returns {Array|NodeList}
    DOM nodes matching the query.

@namespace The root qs namespace.

*/
function qs(query, root) {
  var doc = root ? root.ownerDocument || root :
      (root = qs.global.document);
  return qs.run(qs.cache[query] || qs.compile(query), {
    root: root,
    doc: doc
  }).nodes;
}
/**

A reference to the global object.
@type Object

*/
qs.global = (function () {
  return this || [eval][0]('this');
}());
/**

Holds command arrays, keyed by query string.
@type Object

*/
qs.cache = {};
/**

Various regexen.
@type Object

@private

*/
qs.rx = {
  singletons: /^(?:body|head|title)$/i,
  className: /\.[^\s\.#]+/g,
  id: /#[^\s\.#]+/g,
  tagName: /^[^\s\.#]+/g,
  lTrim: /^\s\s*/,
  rTrim: /\s\s*$/,
  comma: /\s*,\s*/,
  space: /\s+/
};
/**

Check whether a DOM node has a css class.

@param {Node} node 

@param {String} className

@returns {Boolean} true if success, else false.

*/
qs.hasClass = function (node, className) {
  return (' ' + node.className + ' ')
      .indexOf(' ' + className + ' ') > -1;
};
/**

@param {String} text
@returns {String}

*/
qs.trim = function (text) {
  return text.replace(qs.rx.lTrim, '').replace(qs.rx.rTrim, '');
};
/**

Check a DOM node against a qs.Compound object.

@param {Node} node
    The DOM node to check. 

@param {qs.Compound} compound
    An object constructed by qs.Compound, or an equivalent object.

@returns {Boolean} true if success, else false.

*/
qs.check = function (node, compound) {
  var className, i = -1;
  if ((compound.tagName && (compound.tagName !== node.tagName)) ||
      (compound.id && (compound.id !== node.id)) ||
      (!compound.className)) {
    return false;
  }
  while ((className = compound.className[++i])) {
    if (!qs.hasClass(node, className)) {
      return false;
    }
  }
  return true;
};
/**

Create an array of commands, store it in the cache, and return it.

@param {String} queryString

@returns {Array} 
    qs.Command objects to run for this queryString.

*/
qs.compile = function (queryString) {
  var result = [], query = new qs.Query(queryString),
      selectors = query.compounds,
      selector = selectors[0],
      compound, prevChain, i = -1,
      isLast, isSingleton;

  /*  If the normalized query is already cached, create a new 
      reference to the command array in the cache using this
      version of the queryString as the key.

  */
  if (qs.cache[query]) {
    return (qs.cache[queryString] = qs.cache[query]);
  }

  // FIXME: handle groups of selectors (recursive qs call)
  // if (selectors.length > 1) { }

  prevChain = 0;
  while ((compound = selector[++i])) {
    isLast = i === selector.length - 1;
    isSingleton = qs.rx.singletons.test(compound.tagName);
    if (compound.id || isSingleton || isLast) {
      result = result.concat(qs.compoundToChain(
        compound, selector.slice(prevChain, i)
      ));
      prevChain = i + 1;
    }
  }

  return (qs.cache[queryString] = qs.cache[query] = result);
};
/**

Called by qs.compile. Creates an array of commands from a
qs.Compound object.

@param {qs.Compound} compound

@param {Array} ancestorChecks

@returns {Array}
    Array of command objects.

*/
qs.compoundToChain = function (compound, ancestorChecks) {

  var result = [], hasId, hasAncestorChecks, className;

  compound = compound.copy();

  if (qs.rx.singletons.test(compound.tagName)) { 
    result.push({ 
      fn: qs.cmd.getByTag, 
      args: [compound.tagName, true] 
    });
    compound.tagName = false;
  }
  else if (compound.id) { 
    result.push({ 
      fn: qs.cmd.getById, 
      args: [compound.id] 
    });
    hasId = true;
    compound.id = false;
  }
  else if (compound.className[0]) { 
    className = compound.className.shift();
    result.push({ 
      fn: qs.cmd.getByClass, 
      args: [className] 
    });
  }
  else if (compound.tagName) { 
    result.push({ 
      fn: qs.cmd.getByTag, 
      args: [compound.tagName] 
    });
    compound.tagName = false;
  }

  if (compound.id || compound.tagName || 
      (compound.className && compound.className[0])) {
    result.push({ 
      fn: qs.cmd.filter, 
      args: [compound] 
    });
  }
  if (ancestorChecks.length) {
    result.push({ 
      fn: qs.cmd.checkAncestors, 
      args: ancestorChecks 
    });
    hasAncestorChecks = true;
  }
  if (hasId) {
    result.push({ 
      fn: qs.cmd.checkIdRoot 
    });
  }
  return result;

};
/**

Run a set of commands in a given context.

@param {Array} commands
    List of commands to run.

@param {Object} context
    Shared object referenced by `this` in each command.

@returns {Object} context.

*/
qs.run = function (commands, context) {
  var command, i = -1;
  if (!context) {
    context = {};
  }
  while ((command = commands[++i])) {
    if (command.fn.apply(context, command.args)) {
      return context;
    }
  }
  return context;
};
/**

@namespace 

Predefined commands for manipulating a collection of DOM nodes.

@description

*/
qs.cmd = {
  /**

  Get an element by id from the context document,
  and set the context nodes to an array containing the result,
  or an empty array.

  @param {String} id

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  getById: function (id) { // getById
    var e = this.doc.getElementById(id);
    this.nodes = e ? [e] : [];
    return !e;
  },
  /**

  Get a NodeList by class name from the context root,
  and set the context nodes to the result.

  @param {String} className

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  getByClass: function (className) {  // getByClass
    this.nodes = this.root.getElementsByClassName(className);
    return !this.nodes.length;
  },
  /**

  Get a NodeList by tag name from the context root,
  and set the context nodes to the result.

  @param {String} tagName

  @param {Boolean} setRoot
      If true, set the context root to the first found node.

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  getByTag: function (tagName, setRoot) { // getByTag
    this.nodes = this.root.getElementsByTagName(tagName);
    if (setRoot) {
      this.root = this.nodes[0];
    }
    return !this.nodes.length;
  },
  /**

  Filter the context nodes.

  @param {qs.Compound} compound

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  filter: function (compound) { // filter
    var nodes = this.nodes, node, i = -1, result = [];
    while ((node = nodes[++i])) {
      if (qs.check(node, compound)) {
        result.push(node);
      }
    }
    this.nodes = result;
    return !result.length;
  },
  /**

  Check whether the context nodes' ancestors match a chain of 
  compound selectors.

  @param {qs.Compound} compound...
      One argument for each ancestor in the chain. The "oldest"
      ancestor should be the first argument, and the "youngest"
      should be the last.

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  checkAncestors: function (/*...*/) { // checkAncestors
    var root = this.root, nodes = this.nodes, node, result = [],
        check, len = arguments.length, checkIndex = len, i = -1,
        ancestor, topAncestor;
    while ((node = nodes[++i])) {
      ancestor = node;
      check = arguments[--checkIndex];
      while ((ancestor = ancestor.parentNode) && 
            (ancestor !== root)) {
        if (!qs.check(ancestor, check)) {
          continue;
        }
        check = arguments[--checkIndex];
        if (checkIndex < 0) {
          topAncestor = ancestor;
          result.push(node); 
          break;
        }
      }
      checkIndex = len;
    }
    this.topAncestor = topAncestor;
    this.nodes = result;
    return !result.length;
  },
  /**

  Check whether the context node is contained by the root node. 

  This command should be run if the *getById* command has been run. 
  It should run after any *filter* or *checkAncestors* commands 
  immediately following each *getById* command.

  @return {Boolean} 
      true if no more commands should be processed, else false.

  */
  checkIdRoot: function () { // checkIdRoot
    var root = this.root, 
        node = this.topAncestor || this.nodes[0];
    if (!root.ownerDocument) {
      root = this.nodes[0];
      return false;
    }
    while ((node = node.parentNode)) {
      if (node === root) { 
        root = this.nodes[0];
        return false;
      }
    }
    return true;
  }

};
/**

@class 

Stores a compound selector in object form.

@see <a href="http://www.w3.org/TR/selectors4/#structure">
Selectors Level 4: Structure and Terminology
</a>

@param {String} text
    Normalized compound selector text.

*/
qs.Compound = function (text) {
  /**

  CSS class to match.
  @type String

  */
  this.className = (text.match(qs.rx.className) || [])
      .join('').substring(1).split('.');
  /**

  Tag name to match.
  @type String

  */
  this.tagName = ((text.match(qs.rx.tagName) || [])[0] || '')
      .toUpperCase();
  /**

  Id attribute to match.
  @type String

  */
  this.id = ((text.match(qs.rx.id) || [])[0] || '')
      .substring(1);
  this.className.sort();
};

qs.Compound.prototype = {
  /**

  Create a plain object copy of the current object.

  @returns {Object}

  */
  copy: function () { 
    return { 
      id: this.id,
      className: this.className.slice(),  
      tagName: this.tagName
    };
  },
  /**

  Get the normalized version of the compound selector.

  @returns {String} 
      The normalized compound selector.

  */
  toString: function () { 

    return this.normalized ||
        (this.normalized = this.tagName + 
        (this.id ? '#' + this.id  : '') + 
        (this.className[0] ? '.' + this.className.join('.') : ''));
  }
};
/**

@class 

Stores information about a query selector.

@constructor

@param {String} text
    Query selector text.

*/
qs.Query = function (text) {
  var compoundStrings = text.split(qs.rx.comma),
      compound, compounds, i = -1, j,
      original = text;
  while ((text = compoundStrings[++i])) {
    compounds = qs.trim(text).split(qs.rx.space);
    j = -1;
    while ((compound = compounds[++j])) {
      compounds[j] = new qs.Compound(compound);
    }
    compoundStrings[i] = compounds;
  }
  compounds = compoundStrings;
  /**

  The original (non-normalized) query string.
  @type String

  */
  this.original = original;
  /**

  Compound selectors composing the query.
  @type Array

  */
  this.compounds = compounds.sort();
  /**

  Normalized version of the query.
  @type String

  */
  this.normalized = '';
};
/**

Get the normalized version of the original query selector.

@returns {String} 
    The normalized query selector.

*/
qs.Query.prototype.toString = function () { 
  if (this.normalized) { 
    return this.normalized;
  } 
  var compounds = this.compounds, selector, i = -1, result = '';
  while ((selector = compounds[++i])) {
    result += (i ? ', ' : '') + selector.join(' ');
  }
  return (this.normalized = result);
};

Tests:

query
query("li", document)
querySelectorAll
document.querySelectorAll("li")
getElementByTagName
document.getElementsByTagName("li")
qs
qs("li")

Run results for: querySelectorAll vs query vs qs

100 Li elements using querySelectorAll and custom query function got from http://ryanmorr.com/abstract-away-the-performance-faults-of-queryselectorall/ and qs from https://codereview.stackexchange.com/questions/25452/very-fast-query-selector

query

querySelectorAll

getElementByTagName

qs