?????? ???

??? = ??? ?????.

??? +? ?? ???? ? ?????.

Operator =? JavaScript ??? ?? ???? ? ?????.

?? ??? +? ?? ??? ? ?????.

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文網(wǎng)(php.cn)</title> 
</head>
<body>
<p>點(diǎn)擊按鈕計(jì)算 x 的值.</p>
<button onclick="myFunction()">點(diǎn)擊這里</button>
<p id="demo"></p>
<script>
function myFunction()
{
y=5;
z=2;
x=y+z;
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>

????? ???? ??? ???

JavaScript ?? ???

?? ???? ?? ??? ???? ? ?????. ?? ?/?? ? ??? ???? ??.

y=5? ?? ?? ???? ??? ?? ???? ?? ?????.

+ /???x=y/2x=2.5%??? ??(?? ??)x=y%2x=1++ ?? x=++yx=6--decreasingx=--yx=4JavaScript ?? ??? ?? ??? JavaScript ??? ?? ???? ? ?????. x=10 ? y=5? ?? ?? ???? ?? ???? ?????. =yx=5+=x+=yx=x+yx=15-=x-=yx=x-y x= 5*=x*=yx=x*y

x=50

x/=y

x=x/y

x =2

%=x%=yx=x%yx=0

+ ??? ???

+ ???? ??? ??? ??? ??? ??(??)?? ? ?????.

? ? ??? ??? ??? ???? ?? ?? + ???? ?????.

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文網(wǎng)(php.cn)</title> 
</head>
<body>
<p>點(diǎn)擊按鈕創(chuàng)建及增加字符串變量。</p>
<button onclick="myFunction()">點(diǎn)擊這里</button>
<p id="demo"></p>
<script>
function myFunction()
{
txt1="What a very";
txt2="nice day";
txt3=txt1+txt2;
document.getElementById("demo").innerHTML=txt3;
}
</script>
</body>
</html>

????? ???? ??? ???

? ??? ??? ??? ????? ??? ???? ???. ??? ???? ??:

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文網(wǎng)(php.cn)</title> 
</head>
<body>
<p>點(diǎn)擊按鈕創(chuàng)建及增加字符串變量。</p>
<button onclick="myFunction()">點(diǎn)擊這里</button>
<p id="demo"></p>
<script>
function myFunction()
{
txt1="What a very ";
txt2="nice day";
txt3=txt1+txt2;
document.getElementById("demo").innerHTML=txt3;
}
</script>
</body>
</html>

????? ???? ??? ???.

?? ???? ??? ?????.

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文網(wǎng)(php.cn)</title> 
</head>
<body>
<p>點(diǎn)擊按鈕創(chuàng)建及增加字符串變量。</p>
<button onclick="myFunction()">點(diǎn)擊這里</button>
<p id="demo"></p>
<script>
function myFunction()
{
txt1="What a very";
txt2="nice day";
txt3=txt1+" "+txt2;
document.getElementById("demo").innerHTML=txt3;
}
</script>
</body>
</html>

????? ???? ??? ???.

???? ?? ??

? ?? ??? ???? ??? ?? ?????. ??? ???? ???? ???? ?????. ?:

Example

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文網(wǎng)(php.cn)</title> 
</head>
<body>
<p>點(diǎn)擊按鈕創(chuàng)建及增加字符串變量。</p>
<button onclick="myFunction()">點(diǎn)擊這里</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x=5+5;
var y="5"+5;
var z="Hello"+5;
var demoP=document.getElementById("demo");
demoP.innerHTML=x + "<br>" + y + "<br>" + z;
}
</script>
</body>
</html>

Rule: ???? ??? ???? ??? ???? ? ????!

????? ???? ??? ???

???? ??

??? ??

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>php中文網(wǎng)(php.cn)</title> </head> <body> <p>點(diǎn)擊按鈕計(jì)算 x 的值.</p> <button onclick="myFunction()">點(diǎn)擊這里</button> <p id="demo"></p> <script> function myFunction() { y=5; z=2; x=y+z; document.getElementById("demo").innerHTML=x; } </script> </body> </html>

?????? ???

????

?? ?? ?? ??

???? ??

??? ??