高效图形（一）

var Pet = function(name, legs){
    this.name = name;
    this.legs = legs;
};
Pet.prototype.getDetails = function(){
    return this.name + " has " + this.legs + " legs";
};

var Cat = function(name){
    Pet.call(this, name, 4);// Call the parent object's constructor
};
Cat.prototype = new Pet();

Cat.prototype.action = function(){
    return "Catch a bird";
};

// create an instance of Cat in petCat
var petCat = new Cat('Flex');

var details = petCat.getDetails();
console.log("details:", details);
var action = petCat.action();
console.log("action: " , action)
console.log("petCat.name, petCat.legs: ", petCat.name, petCat.legs)
petCat.name = 'Sylvester';
petCat.legs = 7;
console.log("petCat.name, petCat.legs:",petCat.name, petCat.legs)
details = petCat.getDetails();
console.log("details::", details)

//  这种继承方法没有提供对外部继承的保护，在涉及多个程序的复杂项目中这个缺点也许会影响很大。
//  另一个选项无需使用prototype 或new,而是利用javascript的“函数继承”特性来吸收和增强对象实例。

var pet = function(name, legs){
            var that = {
                name : name,
                getDetails : function(){
                    return that.name + " has " + legs + " legs";
                }
            };
                return that;
        };

        var cat = function(name){
            var that = pet(name, 4);

            that.action = function(){
                return 'Cathch a bird!';
            };

            return that;
        };


        var petCat2 = cat('Flexi');
        console.log(petCat2);

        details = petCat2.getDetails();
        console.log("details:", details);

        action = petCat2.action();
        console.log("action:", action);

        petCat2.name = 'Nick';
        console.log("name:::",petCat2.name);
        petCat2.legs = 7;
        console.log("legs:",petCat2.legs)
        details = petCat2.getDetails();
        console.log("details::", details)

var startTime = new Date().getTime();
for(var i = 0; i < 1000; i++){
    pice();
    var  time = new Date().getTime() - startTime;
    console.log(time);
}

var fastSin = function(steps){
    var table = [],
        ang = 0,
        angStep = (Math.PI * 2) / steps;
    do{
        table.push(Math.sin(ang));
        ang += angStep;
    }while(ang < Math.PI * 2);
    return table;
};