JavaScript链式调用实例浅析

function$(){
  var elements = [];
  for(vari=0,len=arguments.length;i<len;++i){
     var element = arguments[i];
     if(typeof element ===”string”){
       element = document.getElementById(element);
     }
     if(arguments.length==1){
        return element;
      }
      elements.push(element);
  }
   return elements;
}

(function(){
  //use private class
   function _$(els){
    this.elements = [];
     for(vari=0,len=els.length;i<len;i++){
      var element = els[i];
       if(typeof element ===”string”){
        element = document.getElementById(element);
       }
       this.elements.push(element)
     }
   }
    //The public interface remains the same.
    window.$ = function(){
       return new _$(arguments);
    }
})();

(function(){
  //use private class
  function _$(els){
    //..省略之前上面的代码
  }
  _$.prototype = {
    each:function(fn){
      for(var i=0,len=this.elements.length;i<len;i++){
        fn.call(this,this.elements[i]);
      }
      return this;
    },
    show:function(prop,val){
      var that = this;
      this.each(function(el){
        that.setStyle("display”,”block");
      });
      return this;
    },
    addEvent:function(type,fn){
      var add = function(el){
        if(window.addEventListener){
         el.addEventListener(type,fn,false);
        }else if(window.attachEvent){
         el.attachEvent("on"+type,fn);
        }
      };
      this.each(function(el){
        add(el);
      });
      return this;
    }
  };
  //The public interface remains the same.
  window.$ = function(){
    return new _$(arguments);
  }
})();

window.installHelper = function(scope, interface) {
  scope[interface] = function() {
   return new _$(arguments);
  }
 };

installHelper(window, '$');
$('example').show();

// Define a namespace without overwriting it if it already exists.
window.com = window.com || {};
com.example = com.example || {};
com.example.util = com.example.util || {};
installHelper(com.example.util, 'get');
(function() {
 var get = com.example.util.get;
 get('example').addEvent('click', function(e) {
  get(this).addClass('hello');
 });
})();

// Accessor without function callbacks: returning requested data in accessors.
window.API = window.API || {};
API.prototype = function() {
 var name = 'Hello world';
 // Privileged mutator method.
 setName: function(newName) {
  name = newName;
  return this;
 },
 // Privileged accessor method.
 getName: function() {
  return name;
 }
}();
// Implementation code.
var o = new API;
console.log(o.getName()); // Displays 'Hello world'.
console.log(o.setName('Meow').getName()); // Displays 'Meow'.
// Accessor with function callbacks.
window.API2 = window.API2 || {};
API2.prototype = function() {
 var name = 'Hello world';
 // Privileged mutator method.
 setName: function(newName) {
  name = newName;
  return this;
 },
 // Privileged accessor method.
 //通过把函数作为参数传入
 getName: function(callback) {
  callback.call(this, name);
  return this;
 }
}();
// Implementation code.
var o2 = new API2;
o2.getName(console.log).setName('Meow').getName(console.log);
// Displays 'Hello world' and then 'Meow'.