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10<! Doct0000ype html>2 345<meta charset= "Utf-8"/>6<title> Small white study javascript</title>78<body onload= "Checkcookie ()" >9 Ten<script> One //Create a new cookie (define a method to create a new cookie) A functionSetcookie (cname,cvalue,eadays) {//set a cookie with a name of CNAME, a value of Cvalue, and a eadays of expiration days - varD =NewDate ();//Define a Date object -D.settime (D.gettime () + (Eadays * 24 * 60 * 60 * 1000));//set an expiration time, getTime () to get the current time + (eadays days * 24 hours * 60 Minutes *60 seconds *1000 mm) Here is the conversion to milliseconds, because GetTime () gets the time in milliseconds the varexpires = "expires=" + d.togmtstring ();//convert the acquired time to a string output -Document.cookie = cname + "=" + Cvalue + ";" + expires;//Output Cookie Cookie name: cookie value; cookie expiry time - }; - + //Read Cookies (define a method to read cookies) - functionGetCookie (CNAME) {//read a cookie named CNAME + varName = CNAME + "=";//define name as cookie name = A varCA = Document.cookie.split (';');//The cookie is separated into an array by a semicolon, which is: [Cookie Name: Cookie value, cookie expiry time] at for(vari = 0; i < ca.length; i++) { - varc = Ca[i].trim ();//remove space at the top of the first CA string - if(C.indexof (name) = = 0)returnC.substring (Name.length, c.length);//if the first occurrence of name in C is equal to 0, that is, at the time of the first one, the character of C subscript (Name.length, c.length) is returned . -}return"";//otherwise returns an empty - - }; in - //Automatic detection of cookies (this is the last place to invoke the decision to decide when to invoke the above two methods) to functionCheckcookie () { + varuser = GetCookie ("username");//defines the method that calls GetCookie () and assigns a value to it username - if(User! = "") {//judge if this method is not empty, that is, when the cookie is not empty theAlert ("Welcome again" + user);//pop up a window that welcomes the user *}Else { $user = prompt ("Please enter your name:", "");//Otherwise, a window will pop up prompting the user to enter a name.Panax Notoginseng if(User! = "" && User! =NULL) {//judge if GetCookie () This method reads to a value, NOT null and NULL when -Setcookie ("username", user, 30);//call Setcookie () to create a new cookie named username with a value of user and a 30-day expiration date. the }; + }; A }; the + - $ $ /*Method Explanation - the Split () method is used to split a string into a string array - var str = "How is you doing today?" the - document.write (Str.split ("") + "<br/>")//Display as: How,are,you,doing,today?Wuyi document.write (Str.split ("") + "<br/>")//Display as: H,o,w,, A,r,e,, Y,o,u,, D,o,i,n,g,, T,o,d,a,y,? the document.write (Str.split ("", 3))//Display as: How,are,you - Wu The //trim () method deletes the string header and trailing spaces, but preserves the spaces inside the string as separate words from the word - About The //indexof () method returns the position of the first occurrence of a specified string value in a string $ - the//substring () method is used to extract the character of a string intermediary between two specified subscripts - var str = "Hello world!" - A document.write (str.substring (3, 7))//Display as: Lo w*/ + the</script> - $ the</body> theJavaScript Learning notes-a simple welcome cookie
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