?????? ?? ????
JavaScript??? ?? ? ?? ??? ??? ? ?? ?????.
JavaScript??? ??? ??? ?? ??? ? ????. ?, ??? ?? ??? ?? ??? ? ????.
?? ? ????? ??? ??? ????.
Instance 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>
x = 5; // 變量 x 設(shè)置為 5
elem = document.getElementById("demo"); // 查找元素
elem.innerHTML = x; // 在元素中顯示 x
var x; // 聲明 x
</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; // 聲明 x
x = 5; // 變量 x 設(shè)置為 5
elem = document.getElementById("demo"); // 查找元素
elem.innerHTML = x;
</script>
</body>
</html> ????? ???? ??? ???
?? ?? ????? "????(?? ????)"? ???? ???.
?? ??: ?? ??? ?? ??? ?? ?????? ?? ??? ??? ? ?? ??? "??"???.
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>????? ???? ??? ???
<!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 ??? ???? ?? ?????.
Tip
???? ??? ?????.
JavaScript ?? ????? ???? ??????? ??? ?? ????.
?????? ?? ??? ? ???? ??? ??? ??? ????? ??? ???? ????.
??? ??? ???? ?? ????? ? ??? ???? ?? ??? ??? ?????. ?? ?? ???? JavaScript ?? ?? ???? ???? ????.
