You can usually find good compatibility information on MDN. For example: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input#Browser_compatibility
That says you are ok as long as you don't care about Internet Explorer 1.0
Question
I don't know why but I just had such a difficult time to find browser support on this property. Which browsers support inputCheckbox.checked
?
Solution
You can usually find good compatibility information on MDN. For example: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input#Browser_compatibility
That says you are ok as long as you don't care about Internet Explorer 1.0
OTHER TIPS
Every browser that supports JavaScript and forms.