files/en-us/web/api/htmlinputelement/checked/index.md
{{ APIRef("HTML DOM") }}
The checked property of the {{DOMxRef("HTMLInputElement")}} interface specifies the current checkedness of the element; that is, whether the form control is checked or not.
The boolean checked property is relevant to the radio (<input type="radio">) and checkbox (<input type="checkbox">) input types.
The presence of the HTML checked attribute indicates the checkbox is checked by default. It does not indicate whether this checkbox is currently checked: if the checkbox's state is changed, this content attribute does not reflect the change; only the HTMLInputElement's checked IDL property is updated. The checked attribute is reflected by the {{domxref("HTMLInputElement.defaultChecked", "defaultChecked")}} property.
When a radio input checked property is true, all other radio inputs with the same {{DOMxRef("HTMLInputElement.name", "name")}} are false. If any radio button in a same-named group of radio buttons is {{DOMxRef("HTMLInputElement.required", "required")}}, as long as one button in the group is checked, the {{domxref('ValidityState')}} object's read-only {{domxref('ValidityState.valueMissing','valueMissing')}} property for each radio button in the group will be false.
A checkbox's value is only included in the submitted data upon form submission if checked is true. The value of the {{DOMxRef("HTMLInputElement.indeterminate")}} property has no effect on a checkbox's checked value.
A boolean.
const inputElement = document.getElementById("contactMail");
console.log(inputElement.checked);
inputElement.checked = true;
{{Specifications}}
{{Compat}}