前端工作总结114-JS-JS创建数组的三种方法

隐式创建
var arr=["Audi","BMW","Volvo"];
直接实例化
var arr=new Array("Audi","BMW","Volvo");
创建数组并给数组元素赋值
    var arr=new Array();
     arr[0]="Audi";
     arr[1]="BMW";
     arr[2]="Volvo";注意：
    console.log(arr.length); //3
     arr[4]='jeep';
     console.log(arr.length); //5
     console.log(arr[3]); //undefined