javascript学习心得之数组

1.js中的数组的长度可变，并且可以存不同类型的值；方法的参数其实就是一个arguments的数组。

        var a= ['123', 1, true];
        a[3] = "test";
        alert(a.length);  //输出4

2.toLocaleString()，toString(),valueOf() 返回的是一串由，分隔的字符串。

如var a= ['123', 1, true];

alert(a.valueOf());  //输出 123,1,true

3,用 join可以用指定的字符分隔，如

如  var a = ['123', 1, true];
        alert(a.join('|'));  //输出 123|1|true

4.数组可以表现的和栈一样，有 push(),pop() 两个方法，遵循后进先出（LIFO）原则

  var a = ['123', 1, true];
        a.push('test','best');
        alert(a.length); //输出5

        var item = a.pop();
        alert(item);//输出best
        alert(a.length);  //输出4

5.数组可以表现的和队列一样，有 push(),shift() 两个方法，遵循先进先出（FIFO）原则

        var a = ['123', 1, true];
        a.push('test'，‘best’);
        alert(a.length); //输出5

       var item = a.shift();
        alert(item);//输出123
        alert(a.length);  //输出4

6.  反转数组项的顺序

    方法一： var values = [1, 2, 3, 4, 5];
      alert(values.reverse());//输出 5,4,3,2,1

   方法二：  function compare(r1, r2) {
            return r2 - r1;
        }
        var values = [1, 2, 3, 4, 5];
        alert(values.sort(compare));

7.数组的连接

  var colors = ["red", "green", "blue"];
        var colors2 = colors.concat("yellow",["black","brown"]);
        alert(colors2);//输出red,green,blue,yellow,black,brown

8.数组的截取

 var colors = ["red", "green", "blue","yellow","purple"];
        alert(colors.slice(1,4));//输出 green,blue,yellow

9.删除，插入，替换

删除：  var colors = ["red", "green", "blue"];
        var removed = colors.splice(0, 1);
        alert(colors);//输出 “green”,"blue"
        alert(removed);//输出 red

插入： var colors = ["red", "green", "blue"];
        var removed = colors.splice(1,0,"yellow","purple");
        alert(colors);//输出red,yellow,purple,green,blue

替换：var colors = ["red", "green", "blue"];
        var removed = colors.splice(1,1,"yellow","purple");
        alert(colors);//输出red,yellow,purple,blue

10，查找元素在数组中的位置  indexOf(),lastIndexOf()