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Simple example of using javascript to implement digit + letter Verification Code

Source: Internet
Author: User
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Example:
Copy codeThe Code is as follows:
<! 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>
<Meta http-equiv = "Content-Type" content = "text/html; charset = gb2312"/>
<Title> js Verification Code </title>
<Style type = "text/css">
. Code
{
Background-image: url(code.jpg );
Font-family: Arial;
Font-style: italic;
Color: Red;
Border: 0;
Padding: 2px 3px;
Letter-spacing: 3px;
Font-weight: bolder;
}
. Unchanged
{
Border: 0;
}
</Style>
<Script language = "javascript" type = "text/javascript">

Var code; // define the verification code globally
Function createCode ()
{
Code = "";
Var codeLength = 4; // The length of the Verification Code
Var checkCode = document. getElementById ("checkCode ");
Var selectChar = new Array (, 'A', 'B', 'C', 'D', 'E', 'F ', 'G', 'h', 'I', 'J', 'k', 'l', 'M', 'n', 'O', 'P ', 'Q', 'R', 's', 't', 'U', 'V', 'ww ', 'x', 'y ', 'Z'); // all the characters whose candidates constitute the verification code. Of course, they can also be in Chinese.

For (var I = 0; I <codeLength; I ++)
{


Var charIndex = Math. floor (Math. random () * 36 );
Code + = selectChar [charIndex];


}
// Alert (code );
If (checkCode)
{
CheckCode. className = "code ";
CheckCode. value = code;
}

}

Function validate ()
{
Var inputCode = document. getElementById ("input1"). value;
If (inputCode. length <= 0)
{
Alert ("Enter the verification code! ");
}
Else if (inputCode! = Code)
{
Alert ("Incorrect verification code! ");
CreateCode (); // refresh the verification code
}
Else
{
Alert ("OK ");
}

}

</Script>
</Head>
<Body onload = "createCode ()">
<Form action = "#">
<Input type = "text" id = "input1"/>
<Input type = "text" onclick = "createCode ()" readonly = "readonly" id = "checkCode" class = "unchanged" style = "width: 80px "/> <br/>
<Input id = "Button1" onclick = "validate ();" type = "button" value = "OK"/>
</Form>
</Body>
</Html>

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