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Today, I reviewed how javascript is used to create and store cookies. I would like to share some of my experiences with you. First, let's take a look at the basic knowledge:
What is cookie?Cookie is a variable stored on the visitor's computer. This cookie is sent every time a computer requests a page through a browser. You can use JavaScript to create and retrieve cookie values.
Examples of cookiesCreate a cookie instance, how to create a cookie, and how to retrieve the cookie.
Javascript code:
// Create cookiefunction setCookie (name, value, expireday) {var exp = new Date (); exp. setTime (exp. getTime () + expireday * 24*60*60*1000); // set the cookie term document. cookie = name + "=" + escape (value) + "; expires" + "=" + exp. toGMTString (); // create cookie} // extract the value of function getCookie (name) {var cookieStr = document. cookie; if (cookieStr. length> 0) {var cookieArr = cookieStr. split (";"); // convert cookie information into an array for (var I = 0; I <cookie Arr. length; I ++) {var cookieVal = cookieArr [I]. split ("="); // convert each cookie (cookie name and value) into an array if (cookieVal [0] = name) {return unescape (cookieVal [1]); // return the cookie value to be extracted }}// test cookiefunction checkCookie () {var cookieUser = document. getElementById ("cookieUser"); var userName = getCookie ("userName"); if (userName) {cookieUser. innerHTML = "hello" + userName + ", welcome back again! ";}Else {var value = prompt (" Enter the user name "," "); if (value) {setCookie ('username', value, 1 );} else {alert ("Enter the user name! ");}}}
The main difference is how to extract the cookie information we need. In this example, the getCookie function converts the cookie information into an array to find the cookie value we need to extract. You can also use the regular expression to match, as shown below:
function getCookie(name) {var cookieStr = document.cookie;var cookieArr = cookieStr.match(new RegExp(name+"=[a-zA-Z0-9]*;$"));var cookieVal = cookieArr.split("=");if(cookieVal[0] == name) {return unescape(cookieVal[1]);}}
For example, in this example, if the cookie named userName is not stored in the browser, the user is prompted to enter the user name. When the page is refreshed again, the entered cookie value is displayed. Finally, we can test the Code:
<body onload="checkCookie()"><p id="cookieUser"></p></body>
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