JavaScript ?? ??
JavaScript ?? ??
JavaScript? ??? ???? ?? ??? function? ?????.
??? ???? ??? ?? ?? ???? ?? ????.
?? ??
?? ?????? ???? ?? ?? ??? ??? ??????.
function functionName(parameters) {
?? ??
}
??? ?? ??? ???? ?? ?????. ??? ? ??? ?????.
?? ???
JavaScript ??? ????? ??? ? ????.
?? ???? ??? ??? ? ????:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p>函數(shù)可以存儲在變量中:</p>
<p id="demo"></p>
<script>
var x = function (a, b) {return a * b};
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>?? ???? ??? ???? ?? ??? ???? ??? ? ????:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p>函數(shù)存儲在變量后，變量可作為函數(shù)使用：</p>
<p id="demo"></p>
<script>
var x = function (a, b) {return a * b};
document.getElementById("demo").innerHTML = x(4, 3);
</script>
</body>
</html>? ??? ??? ?? ?????(???? ??? ????). ).
??? ??? ???? ?? ??? ???? ??? ????? ?? ??? ?? ?????.
? ??? ????? ??? ?????? ????.
Function() ???
?? ??? ??? function ???? ?? ????? ?? ?????.
??? ??? JavaScript ?? ???(Function())? ?? ??? ?? ????.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p>JavaScrip 內(nèi)置構(gòu)造函數(shù)。</p>
<p id="demo"></p>
<script>
var myFunction = new Function("a", "b", "return a * b");
document.getElementById("demo").innerHTML = myFunction(4, 3);
</script>
</body>
</html>?? ????(Hoisting)
??? ?? ?? ?????? "????"? ?? ?????.
????? ?? ??? ??? ????? JavaScript? ?? ?????.
????? ?? ??? ?? ??? ?????.
??? ??? ???? ?? ??? ? ????.
myFunction(5);
function myFunction(y) {
return y * y;
}???? ???? ??? ??? ?? ???? ??????.
?? ?? ??
?? ???? "?? ??"? ?????.
?? ?? ??? ???? ?????.
??? ?? ()? ?? ???? ?????.
??? ??? ?? ??? ? ????.
??? ?????
JavaScript?? typeof ???? ???? ?? ??? ???? "function"? ?????.
??? JavaScript ??? ??? ? ???? ?????.
JavaScript ???? ??? ???? ????.
arguments.length ??? ?? ?? ?? ??? ????? ?? ?????.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p> arguments.length 屬性返回函數(shù)接收到參數(shù)的個數(shù)：</p>
<p id="demo"></p>
<script>
function myFunction(a, b) {
return arguments.length;
}
document.getElementById("demo").innerHTML = myFunction(4, 3);
</script>
</body>
</html>??? ?? ????? ?? ??? ???? ?????.
??? ???? ? ??? ???? ?? ?? ??? ????? ???.
