Creating and storing cookies
In this example we want to create a cookie that stores the visitor's name. When visitors visit the site for the first time, they are asked to fill in their names. The name is stored in the cookie. When visitors visit the site again, they receive a welcome word.
First, we'll create a function that stores the visitor's name in the cookie variable:
| The code is as follows |
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function Setcookie (name, value) { To set a cookie with the name named and value
var expdate = new Date (); Initialization time
Expdate.settime (Expdate.gettime () + 30 * 60 * 1000); Time
Document.cookie = name+ "=" +value+ "expires=" +expdate.togmtstring () + ";p ath=/"; namely document.cookie= name+ "=" +value+ ";p ath=/"; Time can not, but path (path) must be filled out, because the default path JS is the current page, if not filled, this cookie only on the current page in effect! ~
} |
The parameters in the above function hold the name, value, and expiration days of the cookie.
In the above function, we first convert the number of days to a valid date, and then we save the cookie name, value, and its expiration date to the Document.cookie object.
After that, we'll create another function to check if the cookie is set:
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| function GetCookie (c_name)
{
if (document.cookie.length>0)
{
C_start=document.cookie.indexof ( C_name + "=")
if (c_start!=-1)
{
C_start=c_start + c_name.length +1
c_end=document.cookie.indexof (";", C_start)
if (c_end==-1) c_end= Document.cookie.length
return unescape (document.cookie.substring (c_start,c_end))
}
}
Return "
} |
The above function first checks to see if a cookie exists in the Document.cookie object. If the Document.cookie object has certain cookies, it will continue to check that our specified cookie is stored. If we find the cookie we want, we return the value, otherwise we return an empty string.
Finally, we're going to create a function that, if the cookie is set, displays the welcome word, otherwise a prompt box is displayed to require the user to enter a name.
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function Checkcookie ()
{
Username=getcookie (' username ')
if (username!=null && username!= "")
{alert (' Welcome again ' +username+ ')}
Else
{
Username=prompt (' Please enter your name: ', "")
if (username!=null && username!= "")
{
Setcookie (' username ', username,365)
}
}
} |
A complete instance
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| <! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8″/>
<title> Untitled Document </title>
<script type= "Text/javascript" >
function GetCookie (c_name)
{
if (document.cookie.length>0)
{
C_start=document.cookie.indexof (c_name + "=")
if (c_start!=-1)
{
C_start=c_start + c_name.length+1
C_end=document.cookie.indexof (";", C_start)
if (c_end==-1) c_end=document.cookie.length
Return unescape (document.cookie.substring (c_start,c_end))
}
}
Return ""
} function Setcookie (c_name,value,expiredays)
{
var exdate=new Date ()
Exdate.setdate (Exdate.getdate () +expiredays)
document.cookie=c_name+ "=" +escape (value) +
((expiredays==null)? "": "Expires=" +exdate.togmtstring ())
} function Checkcookie ()
{
Username=getcookie (' username ')
if (username!=null && username!= "")
{alert (' Welcome again ' +username+ ')}
Else
{
Username=prompt (' Please enter your name: ', "")
if (username!=null && username!= "")
{
Setcookie (' username ', username,365)
}
}
}
</script>
<body onload= "Checkcookie ()" > </body>
|
It's about the creation of cookies. Let's take a look at a cookie. To save a browsing record instance
The display of the browsing record is read from the cookie and parsed into JSON to generate the HTML element. Because users may have several pages open at the same time, there may be a browse record on each of these pages, in order to refresh it once per second even if the browsing record is displayed.
To use 2 JS files, history.js, key chat records to save and read code. Json.js, the JSON is processed.
History.js
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| var addhistory=function (Num,id) {
Stringcookie=getcookie (' history ');
var stringhistory= ""!=stringcookie?stringcookie: "{history:[]}";
var json=new json (stringhistory);
var e= "{num:" +num+ ", ID:" +id+ "}";
json[' History '].push (e);//Add a new record
Setcookie (' History ', json.tostring (), 30);
}
Show History
var displayhistory=function () {
var P_ele=document.getelementbyid (' history ');
while (P_ele.firstchild) {
P_ele.removechild (P_ele.firstchild);
} var Historyjson=getcookie (' history ');
var json=new json (Historyjson);
var displaynum=6;
For (i=json[' history '].length-1;i>0;i--) {
Addli (json[' history '][i][' num '],json[' history '][i][' ID '), "history");
displaynum--;
if (displaynum==0) {break;}
}
}
Add an LI element
var addli=function (num,id,pid) {
var a=document.createelement (' a ');
var href= ' product.action?pid= ' +id;
A.setattribute (' href ', href);
var t=document.createtextnode (num);
A.appendchild (t);
var li=document.createelement (' Li ');
Li.appendchild (a);
document.getElementById (PID). appendchild (LI);
}
Add cookies
var setcookie=function (c_name,value,expiredays)
{
var exdate=new Date ()
Exdate.setdate (Exdate.getdate () +expiredays)
cookieval=c_name+ "=" +escape (value) + ((expiredays==null)? "": "; expires=" +exdate.togmtstring ());
alert (cookieval);
Document.cookie=cookieval;
}
Get cookies
function GetCookie (c_name)
{
if (document.cookie.length>0)
{
C_start=document.cookie.indexof (c_name + "=")
if (c_start!=-1)
{
C_start=c_start + c_name.length+1
C_end=document.cookie.indexof (";", C_start)
if (c_end==-1) c_end=document.cookie.length
document.write (document.cookie.substring (c_start,c_end) + "<br>");
Return unescape (document.cookie.substring (c_start,c_end))
}
}
Return ""
} |
JSON file
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| Json.js
var JSON = function (Sjson) {
This.objtype = (typeof Sjson);
This.self = [];
(function (S,o) {for (var i in O) {o.hasownproperty (i) && (S[i]=o[i],s.self[i]=o[i])}) (This, (this.objtype== ' string ')? Eval (' 0, ' +sjson): Sjson);
}
Json.prototype = {
Tostring:function () {
return this.getstring ();
},
Valueof:function () {
return this.getstring ();
},
Getstring:function () {
var sA = [];
(function (o) {
var oo = null;
Sa.push (' {');
for (var i in O) {
if (O.hasownproperty (i) && i!= ' prototype ') {
OO = o[i];
if (oo instanceof Array) {
Sa.push (i+ ': [');
for (var b in Oo) {
if (Oo.hasownproperty (b) && b!= ' prototype ') {
Sa.push (oo[b]+ ', ');
if (typeof oo[b]== ' object ') Arguments.callee (oo[b));
}
}
Sa.push ('], ');
Continue
}else{
Sa.push (i+ ': ' +oo+ ', ');
}
if (typeof oo== ' object ') Arguments.callee (OO);
}
}
Sa.push ('}, ');
}) (this.self);
Return Sa.slice (0). Join ('). Replace (/[object object],/ig, '). Replace (/,}/g, '} '). Replace (/,]/g, '] "). Slice (0,-1);
},
Push:function (Sname,svalue) {
This.self[sname] = svalue;
This[sname] = svalue;
}
} |
HTML Document
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| Sample program
<script type= "Text/javascript" src= ". /js/json.js "></script>
<script type=" Text/javascript "src=". /js/history.js "></script>
<ul id=" History "
</ul>
<script>
AddHistory ( 15810782304,2);
AddHistory (64654665,2);
AddHistory (6843212,2);
AddHistory (84984432521,2);
SetInterval ("Displayhistory ()", 1000);
</script> |
