Forms - Disabled & readonly

Web forms are complex beasts. There are a lot of field types to remember, each with dozens of attributes. It’s hard to know which is the right way to go, especially when presented with a choice between two seemingly similar options for disallowing a field to be edited: disabled and readonly.

TL;DR: If you really need it, which you probably don’t, readonly is what you want.

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The Key Difference

So why do we have two attributes that do the same thing? Unfortunately this is where developers often get confused: the user experience is the same, but the mechanics are quite different.

Fields marked as readonly are collected along with all of the normal field values in a form submission (“successful controls” in the spec). The only difference between a readonly field and a regular field is the user experience.

Fields marked as disabled are ignored when collecting values from the form. In a traditional form submission, the action page would never receive values for a disabled field, regardless of whether it has a name attribute.