Question

因此,我有这样的形式:

<form name="login" id="login" action="" method="POST" onSubmit="return test()">
        <input type="text" size="10" name="username" /><div id="wrongUser"></div>
            <br />
        <input type="password" size="10" name="password" /><div id="wrongPass"></div>
            <br />
    <input type="submit" value="submit" name="submit" /><br /><br />
</form>

这两项职能:

function test()
{
    var user = document.login.username.value;
    var pass = document.login.password.value;
    if((user == "" || user == null) && (pass == "" || pass == null))
    {
        document.getElementById( wrongUser ).innerText = "Please Enter Username";
        document.getElementById( wrongPass ).innerText = "Please Enter Password";
        return false;
    }

    if(checkEmpty(user,  wrongUser , "Please Enter Username"))
        return false

    if(checkEmpty(pass,  wrongPass , "Please Enter Password"))
        return false;

    return true;
}

function checkEmpty(name, id, output)
{
    if(name == "" || name == null)
    {
        document.getElementById(id).innerText = "";
        document.getElementById(id).innerText = output;
        return true;
    }
    else
        return false;
}

Now the functions kinda work but not how I would think. If the user only doesn t enter anything (first time) then they get the 2 errors. If the user enter just a username (second time) then the username error should disappear, but it doesn t. If I take it out of the function and replace the variables with their normal values then it works just fine. Why would it change when put in this function?

Answer 1

Put the document.getElementById().innerText = in the other, not in the if. 因为你空洞时只能重新打入内机,但如果它不是空洞的话,你会重新打开该机:

function checkEmpty( name, id, output ) {
  var elem = document.getElementById(id); // it s faster to put the element in a var

  if( name === undefined || name ==    name == null )
    elem.innerText = output;
    return true;
  else
    elem.innerText =   ;
    return false;
}

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