javascript 繼承學習心得總結_基礎知識

function Super(arg){
      this.arr1 = "I'm super "+arg;
      this.show = function(){
        alert(this.arr1);
      }
    }

    Super.prototype.say = function(){
      alert(this.arr1);
    }

    function suber(arg){
      Super.apply(this, arguments); //在suber的上下文中运行super
    }

    var sub =new suber("suber");
    var sub2 = new suber("suber1");

    console.log(sub.arr1); //I'm super suber
    console.log(sub.show); //function (){ alert(this.arr1);}
    console.log(sub.say); //undefined
    console.log(sub.show === sub2.show); //false

function extend(Super,suber){
　　suber = suber || {};
　　for(var i in Super){
　　　　if(Super.hasOwnProperty(i)){
　　　　　　suber[i] = Super[i];
　　　　}
　　　}
　　return suber;
}


var parent = {
  name:"dad",
  num:[1,2,3],
  say:function(){alert("dad");}
}

var child = {
  age:5,
  sex:"boy"
};

child = extend(parent, child);

//以下测试
console.log(child); /*{
             age:5,
             sex:"boy",
             name:"dad",
             num:[1,2,3],
             say:function(){alert("dad");}
            }*/
console.log(child.say === parent.say); //true
console.log(child.num === parent.num); //true

function extenddeep(Super, suber){
      var tostr = Object.prototype.toString, astr = "[object Array]";
      suber = suber || {};

      for(var i in Super){
        if(Super.hasOwnProperty(i)){
          if(typeof Super[i] === "object"){
            suber[i] = (tostr.call(Super[i]) == astr) ? [] : {};
            extenddeep(Super[i],suber[i]);
          }else {
            suber[i] = Super[i];
          }
        }
      }

      return suber;
    }


    var parent = {
      name:"papa",
      num:[1,2,3],
      say:function(){alert("I'm father of my son!");}
    }

    var child = {
      name:"jone",
      sex:"boy",
    }

    var kid = extenddeep(parent, child);

    console.log(kid);  // {name: "papa"
                num: Array[3]
                say: ()
                sex: "boy"
              // }

    console.log(kid.say === parent.say); //true
    console.log(kid.num === parent.num);  //false
    console.log(kid.name); //papa

var one = {
      name:"object",
      say: function(greet){
        return greet + ', ' + this.name;
      }
    }

    var tow = {
      name:"two"
    }

    one.say.call(tow, "hi");  //hi, two

//赋值给一个变量时候上下文会变化
    var say = one.say;
    console.log(say('hoho')); // "hoho, undefined"

    //作为回调函数时也会发生变化
    var yetother = {
      name:"yetother obj",
      method:function(callback){
        return callback("Hola");
      }
    }

    console.log(yetother.method(one.say)); //"Hola, "

function bind(o, m){
      return function(){
        return m.apply(o, [].slice.call(arguments));
      }
    }

    var othersay = bind(yetother, one.say);

    othersay("Hola"); //"Hola, yetother obj"

//这段是直接复制过来的。
    // ECMAScript 5给Function.prototype添加了一个bind()方法，以便很容易使用apply()和call()。

      if (typeof Function.prototype.bind === 'undefined') {
        Function.prototype.bind = function (thisArg) {
          var fn = this,
      slice = Array.prototype.slice,
      args = slice.call(arguments, 1);
          return function () {
            return fn.apply(thisArg, args.concat(slice.call(arguments)));
          };
        };
      }

      var twosay2 = one.say.bind(two);
      console.log(twosay2('Bonjour')); // "Bonjour, another object"

      var twosay3 = one.say.bind(two, 'Enchanté');
      console.log(twosay3()); // "Enchanté, another object"

jQuery.extend = jQuery.fn.extend = function() {
          var options, name, src, copy, copyIsArray, clone,
             target = arguments[0] || {},
             i = 1,
             length = arguments.length,
             deep = false ;

          // Handle a deep copy situation
          //如果第一个参数是boolean类型
          //修正参数,将第二个参数作为target
          if ( typeof target === "boolean" ) {
             deep = target;

              // skip the boolean and the target
             target = arguments[ i ] || {};
              //i++是为了后续 i === length的判断
             i++;
          }

          // Handle case when target is a string or something (possible in deep copy)
          //如果目标既不是对象也不是方法(例如给基本类型扩展属性方法和属性不会报错但是是无用的)，修正target为 js对象
          if ( typeof target !== "object" && !jQuery.isFunction(target) ) {
             target = {};
          }

          // extend jQuery itself if only one argument is passed
          //如果只有一个参数，修正对象为JQuery函数或JQuery对象
          if ( i === length ) {
             target = this ;
              //修正target所在位置,后面的都是要添加给target的对象
             i--;
          }

          for ( ; i < length; i++ ) {
              // Only deal with non-null/undefined values
              if ( (options = arguments[ i ]) != null ) {
                 // Extend the base object
                 for ( name in options ) {
                    src = target[ name ];
                    copy = options[ name ];

                    // Prevent never-ending loop
                    //如果target和copy是同一个对象，略过，防止自己的属性引用了本身对象导致的循环引用,以致GC无法回收
                    if ( target === copy ) {
                        continue ;
                    }

                    // Recurse if we're merging plain objects or arrays
                    //如果是deep为true，并且要添加给target的copy为对象获数组
                    if ( deep && copy && ( jQuery.isPlainObject(copy) || (copyIsArray = jQuery.isArray(copy)) ) ) {
                        if ( copyIsArray ) {
                           copyIsArray = false ;
                           clone = src && jQuery.isArray(src) &#63; src : [];

                       } else {
                           clone = src && jQuery.isPlainObject(src) &#63; src : {};
                       }
                 
                        // Never move original objects, clone them
                        //很巧妙 ,用一个递归,实现引用对象的深克隆,递归的返回条件是属性石基本类型,基本类型都是深克隆
                       target[ name ] = jQuery.extend( deep, clone, copy );

                    // Don't bring in undefined values
                    } else if ( copy !== undefined ) {
                        //浅克隆
                       target[ name ] = copy;
                    }
                 }
             }
          }

          // Return the modified object
          return target;
      };