data.js

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

// The following code is heavily inspired by jQuery's $.fn.data()

(function($){
  var data = {},
      dataAttr = $.fn.data,
      camelize = $.camelCase,
      exp = $.expando = 'Zepto' + (+new Date()),
      emptyArray = [];

  // Get value from node:
  // 1. first try key as given,
  // 2. then try camelized key,
  // 3. fall back to reading "data-*" attribute.
  function getData(node, name) {
    var id = node[exp],
        store = id && data[id];
    if (name === undefined) {
      return store || setData(node);
    } else {
      if (store) {
        if (name in store) {
          return store[name];
        }
        var camelName = camelize(name);
        if (camelName in store) {
          return store[camelName];
        }
      }
      return dataAttr.call($(node), name);
    }
  }

  // Store value under camelized key on node
  function setData(node, name, value) {
    //给node增加一个属性exp
    var id = node[exp] || (node[exp] = ++$.uuid),
      store = data[id] || (data[id] = attributeData(node));
    if (name !== undefined) {
      store[camelize(name)] = value;
    }
    return store;
  }

  // Read all "data-*" attributes from a node
  function attributeData(node) {
    var store = {};
    $.each(node.attributes || emptyArray, function(i, attr){
      if (attr.name.indexOf('data-') == 0) {
        store[camelize(attr.name.replace('data-', ''))] =
            $.zepto.deserializeValue(attr.value);//将value还原
      }
    });
    return store;
  }

  $.fn.data = function(name, value) {
    return value === undefined ?
      // set multiple values via object
      $.isPlainObject(name) ?
        this.each(function(i, node){
          $.each(name, function(key, value){
            setData(node, key, value);
          });
        }) :
        // get value from first element
        (0 in this ? getData(this[0], name) : undefined) :
      // set value on all elements
      this.each(function(){
        setData(this, name, value);
      });
  };

  $.fn.removeData = function(names) {
    if (typeof names == 'string') {
      names = names.split(/\s+/);
    }
    return this.each(function(){
      var id = this[exp], store = id && data[id];
      if (store) {
        $.each(names || store, function(key){
          delete store[names ? camelize(this) : key];
        });
      }
    })
  }

  // Generate extended `remove` and `empty` functions
  //重写remove empty
  ;['remove', 'empty'].forEach(function(methodName){
    var origFn = $.fn[methodName];
    $.fn[methodName] = function() {
      //找出所有节点
      var elements = this.find('*');
      //remove的话再加上自身
      if (methodName === 'remove') {
        elements = elements.add(this);
      }
      elements.removeData();
      return origFn.call(this);
    }
  })
})(Zepto);