?????? ?? ????
?? ??? ??? ??????
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文網(wǎng)(php.cn)</title>
<script type="text/javascript">
var foo = 1;
function bar() {
if (!foo) {
var foo = 10;
}
alert(foo);
}
bar();
</script>
</head>
<body>
</body>
</html>?? ??: 10
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文網(wǎng)(php.cn)</title>
<script type="text/javascript">
var a = 1;
function b() {
a = 10;
return;
function a() {}
}
b();
alert(a);
</script>
</head>
<body>
</body>
</html>?? ??: 1
????? ?? ????? ?? ???, ????, ????? ? ??? ???? ?? ???? ???? JavaScript ?? ??? ?? ??????? ???.
JavaScript ???? ???? ????.
JavaScript ??? ??? ????, ???? ??? ???? ????.
1.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文網(wǎng)(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
var x = 5; // 初始化 x
var y = 7; // 初始化 y
elem = document.getElementById("demo"); // 查找元素
elem.innerHTML = x + " " + y; // 顯示 x 和 y
</script>
</body>
</html>2.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文網(wǎng)(php.cn)</title>
</head>
<body>
<p id="demo"></p>
<script>
var x = 5; // 初始化 x
elem = document.getElementById("demo"); // 查找元素
elem.innerHTML = "x 為：" + x + "，y 為：" + y; // 顯示 x 和 y
var y = 7; // 初始化 y
</script>
</body>
</html>2? y? ???? ?? ??? ????? ?? ??(var y)? ????? ???(y = 7)? ???? ?? ?????. y ??? ???? ?? ?????.
???? ??? ?????.
JavaScript ?? ????? ???? ??????? ??? ?? ????.
?????? ?? ??? ? ???? ??? ??? ???? ????? ??? ???? ????.
??? ??? ???? ?? ????? ? ??? ???? ?? ??? ??? ?????. ?? ???? JavaScript ?? ?? ????? ???? ????.
