Vanilla JS Solution.
In question selected JavaScript tag.
HTML Form:
<form action="/signup">
<div>
<label for="username">User Name</label>
<input type="text" name="username" required/>
</div>
<div>
<label for="password">Password</label>
<input type="password" name="password" />
</div>
<div>
<label for="r_password">Retype Password</label>
<input type="password" name="r_password" />
</div>
<div>
<label for="email">Email</label>
<input type="text" name="email" />
</div>
<input type="submit" value="Signup" disabled="disabled" />
</form>
JavaScript:
var form = document.querySelector('form')
var inputs = document.querySelectorAll('input')
var required_inputs = document.querySelectorAll('input[required]')
var register = document.querySelector('input[type="submit"]')
form.addEventListener('keyup', function(e) {
var disabled = false
inputs.forEach(function(input, index) {
if (input.value === '' || !input.value.replace(/\s/g, '').length) {
disabled = true
}
})
if (disabled) {
register.setAttribute('disabled', 'disabled')
} else {
register.removeAttribute('disabled')
}
})
Some explanation:
In this code we add keyup event on html form and on every keypress check all input fields. If at least one input field we have are empty or contains only space characters then we assign the true
value to disabled
variable and disable submit button.
If you need to disable submit button until all required input fields are filled in - replace:
inputs.forEach(function(input, index) {
with:
required_inputs.forEach(function(input, index) {
where required_inputs
is already declared array containing only required input fields.
JSFiddle Demo: https://jsfiddle.net/ydo7L3m7/