js中的作用域

来源：互联网发布：js中怎么使用map 编辑：程序博客网时间：2024/05/28 23:21

<script>var a = 1;function fn1(){    alert(a);                       // undefined    var a = 2;}fn1();alert(a);                           // 1var a = 1;function fn1(){    alert(a);                       // 1    a = 2;}fn1();alert(a);                           // 2var a = 1;function fn1(a){    alert(a);                       // undefined    a = 2;}fn1();alert(a);                           // 1var a = 1;function fn1(a){    alert(a);                       // 1    a = 2;}fn1(a);alert(a);                           // 1var a = 1;function fn2( a ){    arguments[0] = 3;    alert(a);                                               // 3    var a = 2;    alert( arguments[0] );                                  // 2}fn2(a);alert(a);                                                   // 1</script>

<script>// 想要获取函数内的值：var str = '';function fn1(){    var a = '大鸡腿~';    str = a;}fn1();alert( str );function fn2(){    var a = '9999999克拉钻石23456789';    fn3(a);}fn2();function fn3(a){    alert(a);}</script>

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