javascript - Disable button until required fields are valid - Stack Overflow

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I've searched for the answer to this problem but still can't get this to work:

<script type="text/javascript"> 
$(document).ready(function (){
    validate();
    $('#contact_subject').change(validate);
});

function validate(){
    if ($('#contact_subject').val().length   >   0  {
        $('button').prop('disabled', false);
    }
    else {
       $('button').prop('disabled', true);
    }
}

</script>

I want to make sure #contact_subject has data or else disable the button.

I've searched for the answer to this problem but still can't get this to work:

<script type="text/javascript"> 
$(document).ready(function (){
    validate();
    $('#contact_subject').change(validate);
});

function validate(){
    if ($('#contact_subject').val().length   >   0  {
        $('button').prop('disabled', false);
    }
    else {
       $('button').prop('disabled', true);
    }
}

</script>

I want to make sure #contact_subject has data or else disable the button.

• javascript
• forms
• twitter-bootstrap
• form-submit

Share Improve this question Follow edited Jun 30, 2015 at 15:09 YvesLeBorg 9,08988 gold badges3737 silver badges4949 bronze badges asked Jun 23, 2015 at 16:53 Uriahs VictorUriahs Victor 1,1551515 silver badges3636 bronze badges

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2 Answers 2

Sorted by: Reset to default 5

I think you are missing a bracket ) in if condition

function validate(){
    if ($('#contact_subject').val().length   >   0)  {
        $('button').prop('disabled', false);
    }
    else {
       $('button').prop('disabled', true);
    }
}

Change the event.Try this: http://jsfiddle/e0t7qv56/1/

$("#field").keyup(function(){
    console.log($(this).val().length);
    if($(this).val().length)
        $("#btn").prop('disabled', false);
    else
        $("#btn").prop('disabled', true);
});

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