JavaScript随笔之——函数用法

$(function(){
   // arrowMouseOver();
    Array.prototype.reduce=null;  //将内置reduce函数设置为null
    var eleResult=document.getElementById("result");

    console.log=function(result){
        var text=document.createTextNode(result);
        var br=document.createElement("br");
        //var name=document.createAttribute("data-name");
        eleResult.appendChild(text);
        eleResult.appendChild(br);
        //br.setAttribute(name,"zhu");
    };
    if(typeof Array.prototype.reduce!="function"){
        Array.prototype.reduce=function(callback,initialValue){   //自定义reduce函数
            var previous=initialValue,k= 0,length=this.length;
            if(typeof initialValue==="undefined"){   //如果没传入初始值，则previous等于数组的第一个元素
                previous=this[0];
                k=1;
            }
            if(typeof callback==="function"){
                for(k;k<length;k++){
                    this.hasOwnProperty(k)&&(previous=callback(previous,this[k],this))
                }
            }
            return previous;
        }
    }
    var sum=[1,2,3,4].reduce(function(previous,current,array){
        return previous+current;
    });
    console.log(sum);//10
    var matrix=[
        [1,2],[3,4],[5,6]
    ];
    var flattn=matrix.reduce(function(previous,current){
       return previous.concat(current);
    });
    console.log(flattn);// [1, 2, 3, 4, 5, 6]

});

function Person(name,age){
    this.name=name;
    this.age=age;
    alert("My name is "+arguments[0]+", age is "+ arguments[1]);
    this.sayHello=function(){
        alert("Hello");
    }
}
function Student(name,age,stuID,classID){
    Person.apply(this,arguments);
    this.studentID=stuID;
    this.classID=classID;
}
var person1=new Person("zhu",23);
var student1=new Student("stu1",12,1001,1);