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  • js数组

    1.一维数组

    设置数组求和

    <!DOCTYPE html>
    <html>
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
        var weight=[1.3,2.3,3,4,5,3.21321];
        var sum=0;
        //数组的遍历
        for(var i=0;i<weight.length;i++){
            sum+=weight[i];
            document.write(weight[i]+" ");
        }
        document.writeln("总体重是"+sum+" "+"平均体重"+(sum/weight.length)+"<br/>");
        document.write("体重保留为"+(sum/weight.length).toFixed(3));
            </script>
        </head>
        <body>
        </body>
    </html>
    View Code

    数组的元素可以为任意元素,元素的值可以为任意的类型,

    数组在内存中存在形式,数组为引用类型,

     2.数组细节

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var weight = [1,2,3,4,5,6];
                var sum = 0;
                function abc(arr){
                    weight[0]=9999;
                }
                //数组的遍历
                abc(weight);
                for(var i = 0; i < weight.length; i++) {
                    document.write(weight[i] + " ");
                }
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code

    js中的数组为引用传递

    3.数组的引用基本用法

    越界的话会输出undefined

    不能访问没定义的元素

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var weight = [1, "hello", 2.5];
                window.alert(weight[16]);
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code

     4.js的数组可以动态的增长

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var weight = [1, "hello", 2.5];
                window.alert(weight.length);
                weight[3] = 12;
                window.alert(weight.length);
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code

    5.split函数的用法

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var word = "hello world,大家好";
                var str = word.split(",");
                for(var i = 0; i < str.length; i++) {
                    document.write(str[i] + "<br/>");
                }
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code

    对字符串进行分割

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var word = "hello world,大家好";
                var str = word.split(",");
                for(var i = 0; i < str.length; i++) {
                    document.write(str[i] + "<br/>");
                }
                var str1=word.split("");
                document.write("一个一个的分组"+"<br/>");
                for(var i = 0; i < str1.length; i++) {
                    document.write(str1[i] + "&nbsp;");
                }
                str1=word.split(",",3);
                document.write(str[0]);
                document.write(str1.length);
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code

     6.遍历数组的方式:var key in arr

    <!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="UTF-8">
            <title></title>
            <script language="JavaScript" type="text/jscript">
                var word = "hello world,大家好";
                var str = word.split(",");
                for(var i = 0; i < str.length; i++) {
                    document.write(str[i] + "<br/>");
                }
                var str1=word.split("");
                document.write("一个一个的分组"+"<br/>");
                for(var i = 0; i < str1.length; i++) {
                    document.write(str1[i] + "&nbsp;");
                }
                str1=word.split(",",3);
                document.write(str[0]);
                document.write(str1.length);
            </script>
        </head>
    
        <body>
        </body>
    
    </html>
    View Code
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  • 原文地址:https://www.cnblogs.com/helloworld2019/p/10920625.html
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