enable/disable submit button based in input field (filled/not filled)

Question

what I am missing in this code, If I just want the input submit button to enable/disable/enable.. as long as I fill or unfill the input text? sorry I am doing my best to learn javascript...can anyone help me fix this code?

<form name="myform" method="post">
<input onkeyup="checkFormsValidity();" id="input_id" type="text" name="input_name" value=""/>
<input type="submit" name="submit_name" value="OK" class="submit_class" id="SubmitButton"/>
</form>

<script>
var sbmtBtn = document.getElementById("SubmitButton");
sbmtBtn.disabled = true; 

function checkFormsValidity(){
var myforms = document.forms["myform"];   
    if (myforms.checkValidity()) {
        sbmtBtn.disabled = false;
    } else {
        sbmtBtn.disabled = true;
    }
}
</script>

This is the fiddle: https://jsfiddle.net/1zfm6uck/

Am I missing declaring onLoad mode or something like this? Thanks!

score 3 · Answer 1 · answered Nov 05 '16 at 04:11

Actually - if it wasn't a jsfiddle example your code would work great:

var sbmtBtn = document.getElementById("SubmitButton");
sbmtBtn.disabled = true; 

function checkFormsValidity(){
  var myforms = document.forms["myform"];   
  if (myforms.checkValidity()) {
    sbmtBtn.disabled = false;
  } else {
    sbmtBtn.disabled = true;
  }
}

input[type='submit']:disabled{
 color:red;
}

<form name="myform" method="post">
<input onkeyup="checkFormsValidity();" id="input_id" type="text" name="input_name" value="" required="required" />
<input type="submit" name="submit_name" value="OK" class="submit_class" id="SubmitButton"/>
</form>

The problem was the jsfiddle put your javascript code inside a clousure, so the checkFormsValidity function is not available in the scope of your input.

I added a required="required" to your input to make sure it's a required field (which will affect the checkValidity() of your form).

thanks, so basically I just missed adding required="required" — NotRocketScientist, Nov 05 '16 at 04:20
In your computer/server you probably missed the `required`, yeah. — Dekel, Nov 05 '16 at 04:23

K Scandrett · Accepted Answer · 2016-11-05T04:11:50.190

1

function checkFormsValidity(){

needs to be change to:

checkFormsValidity = function(){

Personally I wouldn't check validity that way, but in terms of making your code work without error, that will do it.

Edit: Also add required="required" to the input.

edited Nov 05 '16 at 04:11

answered Nov 05 '16 at 04:06

K Scandrett

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okey thanks, that does the trick. But have you noticed that if I delete/unfill the input text the submit button does not go back to the disabled mode? How can we fix that? – NotRocketScientist Nov 05 '16 at 04:12
Add `required="required"` to the input – K Scandrett Nov 05 '16 at 04:12

enable/disable submit button based in input field (filled/not filled)

2 Answers2