javaScript中数据类型和数组的案例

迈不过友情╰ 2023-07-21 06:08 56阅读 0赞

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<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>javaScript中数据类型和数组的案例</title>
    </head>
    <body>
    <h1>javaScript中数据类型和数组的案例</h1>
    </body>
    <script type="text/javascript">
    //案例1
    var a = '江西省赣州市于都县';
    console.log(typeof a);
    console.log(typeof (a));
    
    a = 666;
    console.log(typeof a);
    console.log(typeof (a));
    
    function fn1(){
    	return 888;
    }
    
    a = fn1();
    console.log(typeof a);
    console.log(typeof (a));
    
    function fn2(){
    	console.log('我是fn2()函数');
    }
    
    a = fn2();
    console.log(typeof a);
    console.log(typeof (a));
    
    //
    var b = 123;
    console.log(typeof b);
    console.log(typeof (b));
    
    b = '于都县';
    console.log(typeof b);
    console.log(typeof (b));
    
    b = fn3();
    function fn3(){
    	return 835;
    }
    console.log(typeof b);
    console.log(typeof (b));
    
    b = fn4();
    function fn4(){
    	console.log('我是fn4函数');
    }
    console.log(typeof b);
    console.log(typeof (b));
    
    var c = 5;
    console.log(typeof c);
    console.log(typeof (c));
    
    c = null;
    console.log(typeof c);
    console.log(typeof (c));
    
    c = undefined;
    console.log(typeof c);
    console.log(typeof (c));
    
    console.log(typeof null);
    console.log(typeof (null));
    
    console.log(typeof undefined);
    console.log(typeof (undefined));
    
    var d = false;
    console.log(typeof d);
    console.log(typeof (d));
    d = true;
    console.log(typeof d);
    console.log(typeof (d));
    //创建数组的4种语法
    //隐式创建(推荐使用)
    var names = ['苏荃', '曾柔', '阿珂', '建宁公主', '双儿', '沐剑屏', '方怡'];
    var result = Array.isArray(names);
    console.log(result, names.length);
    for ( var name in names) {
    	console.log(name);
    }
    
    //直接实例化
    var citys = new Array('南昌', '赣州', '上饶', '萍乡');
    var result2 = Array.isArray(citys);
    console.log(result2, citys.length);
    for (var index = 0; index < citys.length; index++) {
    	console.log(citys[index]);
    }
    
    //创建数组并指定长度
    var hobbys = new Array(3);
    hobbys[0] = '吃';
    hobbys[1] = '喝';
    hobbys[2] = '嫖';
    var result3 = Array.isArray(hobbys);
    console.log(result3, hobbys.length);
    for (var i = 0; i < hobbys.length; i++) {
    	var hobby = hobbys[i];
    	console.log(hobby);
    }
    //可以再次添加元素，定义的数组大小对此没有影响
    hobbys[3] = '赌';
    hobbys[4] = '骗';
    result3 = Array.isArray(hobbys);
    console.log(result3, hobbys.length);
    for (var i = 0; i < hobbys.length; i++) {
    	var hobby = hobbys[i];
    	console.log(hobby);
    }
    
    //创建数组但不指定长度
    var arr = new Array();  
    arr[0] = 123;
    arr[1] = "abc";
    arr[5] = false;
    console.log(arr[3]);//
    console.log(arr);//
    console.log(arr[10]);//undefined，不会出现数组越界异常
    
    //for in 遍历，未定义的不遍历
    for(var i in arr){
    	console.log(arr[i]);
    }
                
    //数组案例
    var m = [false, "aaa", 123, 'hello', true, 56.78];
    console.log(m);
    console.log(m.length);
    
    var n = new Array(false, "hi", 567, 'jack', true, 15.34);
    console.log(n);
    console.log(n.length);
    
    var h = new Array(6);
    h[0] = 'jack';
    h[1] = "tom";
    h[2] = 1789;
    h[3] = false;
    h[4] = 55.66;
    h[5] = true;
    console.log(h);
    console.log(h.length);
    //可以再次添加元素，定义的数组大小对此没有影响
    h[6] = '于都县渡江大道';
    h[7] = 26;
    console.log(h);
    console.log(h.length);
    
    var k = new Array();
    k[0] = '江西省于都县';
    k[1] = 23456;
    k[5] = false;
    k[12] = 40.56;
    k[16] = true;
    console.log(k);//
    console.log(k.length);
    //
    console.log(k[0], k[1], k[2], k[5], k[7], k[16], k[12]);
    //不会出现数组越界异常
    console.log(k[20]); //
    for ( var element in k) {
    	console.log(element);
    }
    console.log('****************');
    for (var index = 0; index < k.length; index++) {
    	console.log(k[index]);
    }
    </script>
    </html>

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