terms and condition checkbox validation before submit. JS

 

<button type="submit" id="submit_button" disabled>Sign Up</button>

/JavaScript function that enables or disables a submit button depending
//on whether a checkbox has been ticked or not.
function terms_changed(termsCheckBox){
    //If the checkbox has been checked
    if(termsCheckBox.checked){
        //Set the disabled property to FALSE and enable the button.
        document.getElementById("submit_button").disabled = false;
    } else{
        //Otherwise, disable the submit button.
        document.getElementById("submit_button").disabled = true;
    }
}