javascript how to make sure that the user input a text in username box

Question

Is that code right ? I don't know if that function is true also or what and Is it a must to put that function code in the script section

    <script>
 function2(un)
 {
   if (typeof un == "undefined")
   alert("enter text");
 }
</script>

<form>
 Username:
 <input type="text" name="username"/>
 <br/>
 <input type="submit" value="Submit"onclick="function2(username)"/>
</form>

are you trying to check whether your username field is empty or not, or trying to check any particular requirement.. — Soumik Sur, Nov 29 '13 at 08:55
both, i want to know is it empty or not for username and to check the form of an email in another one — user3048637, Nov 29 '13 at 08:59

score 1 · Answer 1 · answered Nov 29 '13 at 08:52

1

Use the easiest HTML5 attribute.

<input type="text" name="username" required />

answered Nov 29 '13 at 08:52

Tom Chung

1,412
9
12

score 0 · Answer 2 · answered Nov 29 '13 at 09:02

Use jQuery.

HTML:

<form>Username:
  <input type="text" name="username" id="username" />
  <input type="submit" value="Submit" id="submit" />
  <span id="out"></span>
</form>

JavaScript:

$("#submit").on("click", function (event) {
    event.preventDefault();
    if ($("#username").val()) {
        $("#out").text($("#username").val());
    } else {
        alert("enter username");
    }
});

http://jsfiddle.net/

score 0 · Answer 3 · answered Nov 29 '13 at 09:29

The Code

<form>
    <input type="text" id="username"/>
    <input type="button" id="btn" value="Submit"/>
</form>

Script:

$('#btn').on('click',function(){
    var uname = $('#username').val();
    if(uname.length == 0){
        alert('empty');
    }
    else if(valid_email(uname)!=true){
        alert('invalid_email');
    }
    else{
        alert('validated');
    }
});

function valid_email(email){
    var reg = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    return reg.test(email);
}

Here is the link The Code

javascript how to make sure that the user input a text in username box

3 Answers3