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Functions of JavaScript
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"Http://www.w3.org/TR/html4/strict.dtd" >
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>js01_hello</title>
<meta name= "Author" content= "Administrator"/>
<script type= "Text/javascript" >
The first way of defining
function fn1 () {
Alert ("Fn1");
}
A function is a very special object, an instance of a function class, in which operations stored in memory are stored by a key-value pair.
Alert (typeof fn1);
Because a function is an object, you can define it by the following way
The following is a copy of the function to complete the assignment, two references do not point to the same object
var fn2 = fn1;
FN2 ();
FN1 = function () {
Alert ("Fnn1");
}
/**
* Although a function is an object, it differs from the object in that it is assigned by reference to the completion object, and the function is done by copying the object.
* So fn1, although changed, does not affect FN2
*/
FN2 ();
FN1 ();
/**
* For objects, the assignment is done by referring to the pointer, and modifying O1 or O2 will modify the two values
*/
var O1 = new Object ();
var O2 = O1;
O2.name = "Leon";
alert (o1.name);
</script>
<body>
</body>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01//en"
"Http://www.w3.org/TR/html4/strict.dtd" >
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>js01_hello</title>
<meta name= "Author" content= "Administrator"/>
<script type= "Text/javascript" >
function sum (num1,num2) {
return num1+num2;
// }
var sum = function (num1,num2) {
return num1+num2;
}
function sum (NUM1) {
return num1+100;
// }
/**
* The space pointed to by sum has been changed from a function with two parameters to a function with only NUM1
* Only NUM1 functions are called at the time of invocation
* Special Note: function parameters and calls are not related, if the function has only one parameter, but it is passed in
* Two parameters, just match one
* So there is no overloaded function in JS
*/
var sum = function (NUM1) {
return num1+100;
}
Functions are defined in the following way
/**
* defined in the following way equals a defined
* function fn (num1,num2) {
* Alert (NUM1+NUM2);
* }
* So through the following example, a full description of the function is an object
*/
var fn = new Function ("Num1", "num2", "Alert (' Fun: ' + (NUM1+NUM2))");
FN (12,22);
Alert (sum (19));
Alert (sum (19,20));
</script>
<body>
</body>
JavaScript Learning Note 05
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