Disable readonly to text box onclicking the button

You can do two things:

HTML:

<input id="myInput"  type="text"  readonly="readonly" /><br />
<input id="myButton" type="submit" value="update" />

JS (option 1): [Demo]

document.getElementById('myButton').onclick = function() {
    document.getElementById('myInput').removeAttribute('readonly');
};

JS (option 2): [Demo]

document.getElementById('myButton').onclick = function() {
    document.getElementById('myInput').readOnly = false;
};

Well, to be simple! You can use jQuery to remove this attribute (jQuery would be simple, you can do this using JS too). Here is the code for that:

$('input[type=submit]').click(function () {
  $('input[type=text]').removeAttr('readonly');
})

https://api.jquery.com/removeAttr/

You need to set readOnly property of element to false

You can use document.getElementById(), it reference to the element by its ID

HTML, Here I have added id to elements

<input type="text" id="myTextBox" name="" value="" readonly="readonly"/><br/>
<input type="submit" id="myButton"  name="" value="update" />

JavaScript, Here you can see readOnly property to false.

document.getElementById('myButton').onclick = function() {
   document.getElementById('myTextBox').readOnly =false;
};

DEMO

Additionally, I would suggest you to use 'type="button"' instead of type="submit"

Related