javaScript中变量的案例(全局变量和局部变量，以及var关键字)

秒速五厘米 2023-07-18 09:29 3阅读 0赞

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<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>javaScript中变量的案例(全局变量和局部变量，以及var关键字)</title>
    </head>
    <body>
    <h1>javaScript中变量的案例(全局变量和局部变量，以及var关键字)</h1>
    </body>
    <script type="text/javascript">
    //案例1
    var a = 55;
    var b = 66;
    
    function fn1(){
    //在函数中，没有使用var关键字声明的变量是全局变量
    	a = 88; //全局变量(该变量没有使用var关键字声明)
    	b = 99; //全局变量(该变量没有使用var关键字声明)
    	console.log(a); //88
    	console.log(b); //99
    }
    fn1();
    console.log(a); //88
    console.log(b); //99
    
    //案例2
    var c = 100;
    var d = 200;
    
    function fn2(){
    	var c = 300; //局部变量(该变量是使用var关键字声明的变量)
    	var d = 400; //局部变量(该变量是使用var关键字声明的变量)
    	console.log(c); //300
    	console.log(d); //400
    }
    fn2();
    console.log(c); //100
    console.log(d); //200
    </script>
    </html>

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2N6aDUwMA_size_16_color_FFFFFF_t_70 2]: /images/20230528/f810870ccfa24efe946a42b5a6660613.png