Javascript笔记02：严格模式的特定要求

1.严格模式变量必须声明，不然会报错：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>严格模式</title>
</head>

<body>
<script type="text/javascript">
"use strict";
try {
    i = 1;
}catch(err) {
    alert(err);
}
</script>
</body>
</html>

这里i没有使用var修饰，就是没有定义的意思，后抛出"undeclared variable i"错误

2.严格模式下，不能删除全局变量、函数和函数的参数

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>严格模式</title>
</head>

<body>
<script type="text/javascript">
"use strict";
var i;
function myfunc() {};
delete i;//语法错误
delete myfunc();//语法错误

function myfunc2(arg) 
{ 
   delete arg;//语法错误

}

</script> 
</body> 
</html>