HTMLInputElement: defaultChecked property

The defaultChecked property of the HTMLInputElement interface specifies the default checkedness state of the element. This property reflects the <input> element's checked attribute.

The boolean checked attribute is valid for the radio (<input type="radio">) and checkbox (<input type="checkbox">) input types. The presence of the attribute sets the defaultChecked property to true.

const inputElement = document.getElementById("contactMail");
console.log(inputElement.defaultChecked);