javaScript中instanceof和typeof知识点

电玩女神 2022-11-13 12:29 250阅读 0赞

**直接上代码和截图**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 2][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 5][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 6][]

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>javaScript中instanceof和typeof知识点</title>
    <style type="text/css">
    input[type=button] {
    	background-color: #8E388E;
    	border: 0px solid #8E388E;
    	color: #fff;
    	width: 160px;
    	height: 40px;
    	border-radius: 6px; /*把边框做成圆角*/
    }
    
    </style>
    <script type="text/javascript">
    //window对象有name属性
    console.log("*****", name, "#####");
    console.log("*****", name, window.name, window, "#####");
    
    function fn() {
    	//
    	console.log("***1***", arguments.callee);
    	//***2*** function function
    	console.log("***2***", typeof arguments.callee, typeof(arguments.callee));
    	//***3*** true
    	console.log("***3***", arguments.callee instanceof Function);
    }
    
    fn();
    
    console.log("*************");
    var roles = new Array("建宁公主", "沐剑屏", "双儿", "曾柔");
    //object object true true
    console.log(typeof roles, typeof(roles), roles instanceof Object, roles instanceof Array);
    var dog = {name : "旺财", age : 3, hobby : "啃骨头"};
    //object object true false
    console.log(typeof dog, typeof(dog), dog instanceof Object, dog instanceof Array);
    console.log("*************");
    
    function Aoo(){}
    function Foo(){}
    Foo.prototype = new Aoo();//javaScript原型继承
    var foo = new Foo();
    //instanceof表示的就是原型链的结构
    console.log("***666***", foo instanceof Foo)//***666*** true
    console.log("**888***", foo instanceof Aoo)//**888*** true
    
    var cat = {name : "HelloKitty", age : 2};
    var c2 = cat;
    //***A*** object object true
    console.log("***A***", typeof(cat), typeof cat, cat instanceof Object);
    //***B*** object object true
    console.log("***B***", typeof(c2), typeof c2, c2 instanceof Object);
    //***C*** true true
    console.log("***C***", c2 == cat, c2 === cat);
    
    
    console.log("***D***", Object instanceof Function) //***D*** true
    
    console.log("***E***", Function instanceof Object) //***E*** true
    
    console.log("***F***", Function instanceof Function) //***F*** true
    
    var a = "江西省赣州市于都县";
    var b = 66;
    var c = 88.99;
    var d = true;
    var h = null;
    var k;
    var x = {};
    var y = [];
    var z = new Array("黄晓明", "周杰伦", "范冰冰");
    var p = function() {console.log("hello everyone")};
    //***80*** false false
    console.log("***80***", a instanceof String, b instanceof Number);
    //***81*** false false
    console.log("***81***", c instanceof Number, d instanceof Boolean);
    //***82*** false false
    console.log("***82***", h instanceof Object, k instanceof Object);
    //***83*** true true true
    console.log("***83***", x instanceof Object, y instanceof Object, y instanceof Array);
    //***84*** true true true true
    console.log("***84***", z instanceof Object, z instanceof Array, p instanceof Function, p instanceof Object);
    
    //instanceof操作符用来判断引用类型
    
    //***85*** false false
    console.log("***85***", a instanceof Object, b instanceof Object);
    //***86*** false false
    console.log("***86***", c instanceof Object, d instanceof Object);
    //***87*** false false
    console.log("***87***", null instanceof Object, undefined instanceof Object);
    //***88*** string number
    console.log("***88***", typeof a, typeof b);
    //***89*** number boolean
    console.log("***89***", typeof c, typeof d);
    //***90*** object undefined object undefined
    console.log("***90***", typeof h, typeof k, typeof null, typeof undefined);
    //***91*** object object object function
    console.log("***91***", typeof x, typeof y, typeof z, typeof p);
    //***92*** true false
    console.log("***92***", null == undefined, null === undefined);
    //***93*** false false
    console.log("***93***", null == Object, null === Object);
    //***94*** object false boolean boolean
    console.log("***94***", typeof null, typeof null == Object, typeof (null == Object), typeof (null === Object));
    //***95*** object true true
    console.log("***95***", typeof null, typeof null == "object", typeof null === "object");
    //***96*** object boolean boolean
    console.log("***96***", typeof null, typeof (null == "object"), typeof (null === "object"));
    //***97*** object true true
    console.log("***97***", typeof null, (typeof null) == "object", (typeof null) === "object");
    
    console.log("*************");
    
    function fn1() {
    	var testStr = "[object Object]";
    	//slice(startIndex, endIndex)注意：不包括endIndex
    	//-1表示最后一个字符的下标位置，-2表示倒数第二个字符的下标位置，-3，-4等等，以此类推
    	console.log(testStr, testStr.slice(8, -1));
    	//赣州市于都县渡江大
    	console.log(testStr, "江西省赣州市于都县渡江大道".slice(3, -1));
    }
    </script>
    </head>
    <body style="background-color: #CCE8CF;">
    <h1>javaScript中instanceof和typeof知识点</h1>
    <input type="button" value="字符串的slice()函数" onclick="fn1();">
    <div id="div1" style="background-color: Wheat; height: 100%;">
    </div>
    </body>
    </html>

最近比较懒，这样不好不好！

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70]: /images/20221022/ae718851fae647f9906bf918d7f32e97.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20210327030809159.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/2021032703132358.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20210327031425452.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 4]: https://img-blog.csdnimg.cn/2021032703151468.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 5]: https://img-blog.csdnimg.cn/20210327031717667.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 6]: https://img-blog.csdnimg.cn/20210327031817865.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA==,size_16,color_FFFFFF,t_70