HTML "readonly" input value can be edit when checked a check box

I have a input <input type="text" value="1" readonly id='aaa'/>.

I would like to give it a function when user check the box then can edit the value of id=aaa.

Sample:

<input type="text" value="1" readonly/> <input type="checkbox" /> Checked this if you want to edit the value.

Thank you.