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This article introduces the relevant knowledge of "how to write Ajax without refresh to determine whether the code is empty or not when registering a user name". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The copy code is as follows:

Var xmlHttp

UName () / / when the user name loses focus

{

If (all.uname.== "")

{

All. L1 [XSS _ clean] = "cannot be empty!"

SetTimeout ("close (1)", 1500)

Return

}

Else

{

XmlHttp=new ActiveXObject ("Microsoft.XMLHTTP")

XmlHttp.onreadystatechange=deal; / / callback function

Var url= "aJax.aspx?user='" + all.uname.+ "'"; / / will jump to the page where the user name is detected

XmlHttp.open ("get", url,true); / / submit the form to url in get mode; and start one-step processing

XmlHttp.send (null); / / send

}

}

Deal ()

{

/ / alert (xmlHttp.readystate+ "_ _" + xmlHttp.status)

If (xmlHttp.readystatestatekeeper 4)

{return;}

If (xmlHttp.statusdatabase 200) / / equals 500 is an error in the sql statement or database

{return;}

/ /

Var num = xmlHttp.responseText; / / receive the information sent by the server

/ / alert (num)

All.l1.innerText= ""

If (num > 0)

{

All.l1.innerText= "secondary user name is already in use!"

}

Else

{

All.l1.innerText= "√"

}

}

This is the end of the content of "how to write Ajax without refresh to determine whether the code is empty or used when registering a user name". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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