How to Add a “Readonly” Attribute to an?

Use $.prop()

$("#descrip").prop("readonly",true);

$("#descrip").prop("readonly",false);

Readonly is an attribute as defined in html, so treat it like one.

You need to have something like readonly="readonly" in the object you are working with if you want it not to be editable. And if you want it to be editable again you won't have something like readonly='' (this is not standard if I understood correctly). You really need to remove the attribute as a whole.

As such, while using jquery adding it and removing it is what makes sense.

Set something readonly:

$("#someId").attr('readonly', 'readonly');

Remove readonly:

$("#someId").removeAttr('readonly');

This was the only alternative that really worked for me. Hope it helps!

.attr('readonly', 'readonly') should do the trick. Your .attr('readonly') only returns the value, it doesn't set one.

I think "disabled" excludes the input from being sent on the POST

You can disable the readonly by using the .removeAttr;

$('#descrip').removeAttr('readonly');

For enabling readonly:

$("#descrip").attr("readonly","true");

For disabling readonly

$("#descrip").attr("readonly","");

Use the setAttribute property. Note in example that if select 1 apply the readonly attribute on textbox, otherwise remove the attribute readonly.

document.getElementById("box1").onchange = function(){
  if(document.getElementById("box1").value == 1) {
    document.getElementById("codigo").setAttribute("readonly", true);
  } else {
    document.getElementById("codigo").removeAttribute("readonly");
  }
};

<input type="text" name="codigo" id="codigo"/>

<select id="box1">
<option value="0" >0</option>
<option value="1" >1</option>
<option value="2" >2</option>
</select>