selector.js

//     Zepto.js
//     (c) 2010-2015 Thomas Fuchs
//     Zepto.js may be freely distributed under the MIT license.

//重写zepto.matches与qsa,加上了对:的支持
;(function($){
  var zepto = $.zepto, oldQsa = zepto.qsa, oldMatches = zepto.matches;

  function visible(elem){
    elem = $(elem);
    //无高宽也视为不可见
    return !!(elem.width() || elem.height()) && elem.css("display") !== "none";
  }

  // Implements a subset from:
  // http://api.jquery.com/category/selectors/jquery-selector-extensions/
  //
  // Each filter function receives the current index, all nodes in the
  // considered set, and a value if there were parentheses. The value
  // of `this` is the node currently being considered. The function returns the
  // resulting node(s), null, or undefined.
  //
  // Complex selectors are not supported:
  //   li:has(label:contains("foo")) + li:has(label:contains("bar"))
  //   ul.inner:first > li
  var filters = $.expr[':'] = {
    visible: function(){
      if (visible(this)) {
        return this;
      }
    },
    hidden: function(){
      if (!visible(this)) {
        return this;
      }
    },
    selected: function(){
      if (this.selected) {
        return this;
      }
    },
    checked: function(){
      if (this.checked) {
        return this;
      }
    },
    parent: function(){
      return this.parentNode;
    },
    first: function(idx){
      if (idx === 0) {
        return this
      }
    },
    last: function(idx, nodes){
      if (idx === nodes.length - 1) {
        return this
      }
    },
    eq: function(idx, _, value){
      if (idx === value) {
        return this
      }
    },
    contains: function(idx, _, text){
      if ($(this).text().indexOf(text) > -1) {
        return this
      }
    },
    has: function(idx, _, sel){
      if (zepto.qsa(this, sel).length) {
        return this
      }
    }
  };

  var filterRe = new RegExp('(.*):(\\w+)(?:\\(([^)]+)\\))?$\\s*'),
      childRe  = /^\s*>/,
      classTag = 'Zepto' + (+new Date());

  //预处理selector
  function process(sel, fn) {
    // quote the hash in `a[href^=#]` expression
    sel = sel.replace(/=#\]/g, '="#"]');
    var filter, arg, match = filterRe.exec(sel);
    if (match && match[2] in filters) {
      filter = filters[match[2]];//得到filter函数
      arg = match[3];//filter函数参数
      sel = match[1];//前部select
      if (arg) {
        var num = Number(arg);
        if (isNaN(num)) {
          arg = arg.replace(/^["']|["']$/g, '');
        } else {
          arg = num;
        }
      }
    }
    return fn(sel, filter, arg);
  }

  //重写qsa方法
  zepto.qsa = function(node, selector) {
    return process(selector, function(sel, filter, arg){
      try {
        var taggedParent;
        if (!sel && filter) {
          sel = '*';
        } else if (childRe.test(sel)) {
          // support "> *" child queries by tagging the parent node with a
          // unique class and prepending that classname onto the selector
          taggedParent = $(node).addClass(classTag);
          sel = '.'+classTag+' '+sel;
        }

        var nodes = oldQsa(node, sel);
      } catch(e) {
        console.error('error performing selector: %o', selector);
        throw e;
      } finally {
        if (taggedParent) {
          taggedParent.removeClass(classTag);
        }
      }
      return !filter ? nodes :
        zepto.uniq($.map(nodes, function(n, i){
          return filter.call(n, i, nodes, arg);
        }));
    });
  };

  zepto.matches = function(node, selector){
    return process(selector, function(sel, filter, arg){
      return (!sel || oldMatches(node, sel)) &&
        (!filter || filter.call(node, null, arg) === node);
    });
  };
})(Zepto);