javascript 数组的简单应用

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script type="text/javascript">
        //一、创建数组
        //1.创建空数组
        var arr = new Array();
        console.log(arr.length);
        //2.创建具有长度的数组
        var arr2 = new Array(10);
        console.log(arr2.length);
        //3.创建一个带元素的数组
        var arr3 = new Array(123,true,"hello",new Date());
        console.log(arr3.length);
        console.log(arr3);
        //4.创建一个带元素的数组2
        var arr4 = [123];
        console.log(arr4.length)
        console.log("--------------------");

        //二、属性
        //length属性：表示数组的长度
        console.log(arr3);
        arr3.length = 0; //清空数组
        console.log(arr3);
        arr3.length = 4;
        console.log(arr3);
        console.log("--------------------");
        //三、方法
        var arrdemo = new Array(123,true,"hello",new Date(),444333);
        //join()：指定一个字符，用该字符连接数组的每一个元素，并作为一个字符串返回
        console.log(arrdemo.join("-"));

        //push()：向数组的末尾添加一个元素，返回数组的新长度
        result = arrdemo.push("world");
        console.log(result);
        console.log(arrdemo);

        //pop()：从数组末尾取出一个元素，并返回该元素本身
        result = arrdemo.pop();
        console.log(result);
        console.log(arrdemo);

        //shift()：从数组头部取出一个元素，并返回该元素本身
        result = arrdemo.shift();
        console.log(result);
        console.log(arrdemo);

        //unshift()：向数组的头部添加一个元素，返回数组的新长度
        result = arrdemo.unshift("bbb");
        console.log(result);
        console.log(arrdemo);

        //concat()：拼接数组，并作为一个新的数组返回
        var a1 = [123,345];
        var a2 = ["aaa","bbb"];
        var a3 = [new Date()];
        var newarr = a1.concat(a2,a3);
        console.log(newarr);

        //reverse()：反转数组
        newarr.reverse();
        console.log(newarr);

        //sort()：自然顺序
        var sortarr = [4534,22,66,88,123,"A","a","ab","ba","abc","bac"];
        sortarr.sort();
        console.log(sortarr);

        //splice()：删除指定位置，指定长度的元素，并在该位置添加新的元素
        var s1 = ["aa","fsfas","123",123,123,444,555,666];
        s1.splice(0,3,"cqm");
        console.log(s1);

        //slice()：截取子数组
        var s2 = s1.slice(3,5);
        console.log(s2);
        console.log(s1);

 </script>
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javascript 数组的简单应用

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