JS aspx Verification Code image; JS sets the form mouse style; JS gets all links on the page; JS onchange event, try throw catch for form verification; JS shields all images on the page;

1. Principle: Image src = ASPX page, which generates Verification Code Images

The verification code generated by aspx is stored in the cookie ["yanzhengma "].

Log on to the client and read the verification code from the cookie to check whether it is consistent with the entered one.

 

JSCode

 /*  Password verification trigger: click Login  */  Function  Checkusrpsw (){  VaR Username = Document. getelementbyid ("username" ). Value;  VaR Password = Document. getelementbyid ("password" ). Value; If (Document. getelementbyid ("username"). value = "") {alert ("username cannot be blank "); Return  ;}  If (Document. getelementbyid ("password"). value = "") {alert ("password cannot be blank "); Return  ;}  VaR Checkcode = getcookie ("yzmcode" );  If (Checkcode. tolowercase ()! = Document. getelementbyid ("inpcheckcode"). value. tolowercase () {alert ("Incorrect verification code "); Return  ;}  VaR Pajax = New  Ajax ();  VaR Url = encodeuri ("addedhandlers/login. ashx? Type = login & paras = "+ username +", "+ Password); pajax. Post (URL,  Null , False , Function  (Info ){  VaR Status = Info. responsetext;  If (Status! = "Success" ) {Alert (Status );} Else {Location. href = "index.htm" ;}});}  /*  Refresh Verification Code  */  Function  Changecheckcode (){  VaR I = Math. Random (); document. getelementbyid ( "Imgcheckcode"). src = "aspxpages/imagecode. aspx? I = "+ I; //  Refresh img  }  /*  Get cookie */  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 "" } 

 

Html

 <  TD  > <  Input  Name  = ""  ID  = "Inpcheckcode"  Type  = "Text"  Class = "Text_bgs"   />              <  A  Href  = "#"  Class  = "Yzm_img"  >  <! --    -->                  <  IMG  SRC  = "Aspxpages/imagecode. aspx" ALT  = "Verification code"  ID  = "Imgcheckcode"  Onclick  = "Changecheckcode ()"  Title  = "Cannot see clearly? Click to change the verification code"  />              </  A  > </  TD  > 

 

Aspx code

Using system; using system. data; using system. configuration; using system. collections; using system. web; using system. web. security; using system. web. ui; using system. web. UI. webcontrols; using system. web. UI. webcontrols. webparts; using system. web. UI. htmlcontrols; using system. drawing. design; using system. drawing; public partial class _ default: system. web. UI. page {protected void page_load (Object sender, eventargs e) {This. createcheckcodeimage (rndnum ();} private string rndnum () {int number; char code; string checkcode = string. empty; system. random random = new random (); For (INT I = 0; I <4; I ++) {number = random. next (); If (Number % 2 = 0) code = (char) ('0' + (char) (Number % 10); else code = (char) ('A' + (char) (Number % 26); checkcode + = code. tostring ();} response. cookies. add (New httpcookie ("yzmcode", checkcode); Return checkcode;} private void createcheckcodeimage (string checkcode) {If (checkcode = NULL | checkcode. trim () = string. empty) return; system. drawing. bitmap image = new system. drawing. bitmap (INT) math. ceiling (checkcode. length * 12.5), 22); graphics G = graphics. fromimage (image); try {// generate random generator random = new random (); // clear the image background color G. clear (color. white); // specifies the background noise line of the image. For (INT I = 0; I <25; I ++) {int X1 = random. next (image. width); int X2 = random. next (image. width); int Y1 = random. next (image. height); int y2 = random. next (image. height); G. drawline (new pen (color. silver), X1, Y1, X2, Y2);} Font font = new system. drawing. font ("Arial", 12, (system. drawing. fontstyle. bold | system. drawing. fontstyle. italic); system. drawing. drawing2d. lineargradientbrush brush = new system. drawing. drawing2d. lineargradientbrush (New rectangle (0, 0, image. width, image. height), color. blue, color. darkred, 1.2f, true); G. drawstring (checkcode, Font, brush, 2, 2); // foreground noise of the image to be painted for (INT I = 0; I <100; I ++) {int x = random. next (image. width); int y = random. next (image. height); image. setpixel (X, Y, color. fromargb (random. next ();} // draw the border line G of the image. drawrectangle (new pen (color. silver), 0, 0, image. width-1, image. height-1); system. io. memorystream MS = new system. io. memorystream (); image. save (MS, system. drawing. imaging. imageformat. GIF); response. clearcontent (); response. contenttype = "image/GIF"; response. binarywrite (Ms. toarray ();} finally {G. dispose (); image. dispose ();}}}

 

ASPX page

<% @ Page Language = "  C #  " Autoeventwireup = "  True  " Codefile = "  Imagecode. aspx. CS  " Inherits = "  _ Default  " %> <! Doctype HTML public " -// W3C // dtd xhtml 1.0 transitional // en  "   "  Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd  " > <HTML xmlns = "  Http://www.w3.org/1999/xhtml  " > <Head runat = "  Server  " > <Title>  "  Form1 " Runat = "  Server  " > </Form> </body> 
 
Ii. Set the format mouse Style
 

 
Document. Body. style. cursor = "crosshair ";
 
 
Document. Body. style. cursor = "default ";
 
 
3. Document. Links get all links on the page
 

 
 

VaRLinks =Document. links;VaRArnames =[];For(VaRIInLinks) {arnames. Push (Links [I]);}For(VaRIInArnames) {document. Write (arnames [I]);}
 
 
Usage: Use the firebug plug-in of Firefox to run on the Sina homepage.
 

 
 
 

 
4. js onchange event, try throw catch for Form Verification
 

<! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <HTML xmlns = "http://www.w3.org/1999/xhtml">  /*  (1) loss of focus (2) content has changed while meeting (1), (2) trigger onchange ------- throw:ProgramStream to catch (e) --------- carch (e): E can be any variable name  */  Function  Checkinfo (ID ){  Try  {  If (ID = "usrname" ){  If (Document. getelementbyid (ID). value = ""){ //  Throw, the program flow directly to catch               Throw "User name cannot be blank" ;}  If (Document. getelementbyid (ID). value. length> 20 ){  Throw "The length of the user name cannot exceed 20" ;}}  Else   If (ID = "psw" ){  If (Document. getelementbyid (ID). value = ""){  Throw "The password cannot be blank" ;}  If (Document. getelementbyid (ID). value. length> 20 ){  Throw "The password length cannot exceed 20" ;}  If  (Isnan (document. getelementbyid (ID). Value )){  Throw "The password must be a numerical value" ;}}}  Catch (E ){//  Arbitrary variable name  Alert (e );}} </SCRIPT>  User Name <Input type = "text" id = "usrname" onchange = "checkinfo (this. ID)"/> <br/> Password & Nbsp; Code <input type = "text" id = "psw" onchange = "checkinfo (this. ID) "/> </div> </body> 
 
5. js shields all images on the webpage;
 

VaRImages =Document. images;For(VaRIInImages) {images [I]. style. Visibility= "Hidden";}
 
 
Tutorial method: firebug, Which is used on the Sina homepage;
 

 
Effect: Images in IFRAME cannot be removed.