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JavaScript Learning Note 06

Source: Internet
Author: User
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function, function can return a function directly

<! 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>

<! 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" >
/**
* Because the function is an object, you can pass the function directly through the parameters.
*/
function Callfun (fun,arg) {
The first argument is a function object
return Fun (ARG);
}

function sum (num) {
return num+100;
}

function say (str) {
Alert ("Hello" +str);
}
var say = xxx
Called the Say function
Callfun (say, "Leon");
The SUM function is called
Alert (Callfun (sum,20));

function Fn1 (ARG) {
/**
* A function object is returned at this time
*/
var rel = function (num) {
return arg+num;
}
return rel;
}
At this point, F is a function object that can complete the call
var f = fn1 (20);
Alert (f (20));
Alert (f (11));
</script>
<body>
</body>

function, function can directly return a function, to flexibly implement the function sort

<! 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"/>

<body>
<div id= "Person" ></div>
<script type= "Text/javascript" >
/**
* Functions that are sorted according to numbers
*/
function Sortbynum (A, b) {
Return parseint (a)-parseint (b);
// }
Alert ("11" + 1);
Conversion is done automatically when subtraction occurs
Alert ("11"-1);
var as = [11px "," 12px ", 190];
For JS, the default is to sort by string.
As.sort (Sortbynum);
alert (AS);

Testing is sorted by object
function Person (name,age) {
THIS.name = name;
This.age = age;
}
var p1 = new Person ("Leno", 39);
var p2 = new Person ("John", 23);
var p3 = new Person ("Ada", 41);
var PS = [P1,P2,P3];
Ps.sort (Sortbyage);
p1.name,p1["Name"]
/**
* Use the following methods to handle sorting, the problem is that you need to set a function for each property, obviously not flexible
* But it's different if you call through the function's return value.
*/
function Sortbyname (obj1,obj2) {
if (obj1.name>obj2.name) return 1;
else if (Obj1.name==obj2.name) return 0;
else return-1;
// }
function Sortbyage (obj1,obj2) {
return obj1.age-obj2.age;
// }
//
Ps.sort (Sortbyproperty ("Age"))
function Sortbyproperty (PropertyName) {
var sortfun = function (obj1,obj2) {
if (Obj1[propertyname]>obj2[propertyname]) return 1;
else if (Obj1[propertyname]==obj2[propertyname]) return 0;
else return-1;
}
return sortfun;
}
Function Show () {
var p = document.getElementById ("person");
for (Var i=0;i<ps.length;i++) {
P.innerhtml+=ps[i].name+ "," +ps[i].age+ "<br/>";
}
}
Show ();
</script>
</body>

JavaScript Learning Note 06

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