CODE EXAMPLE FOR HTML

how to enable a button when a checkbox is selected in javascript

<input onclick="alert('thank you for agreeing to the terms and conditions')" type="submit" name="sendNewSms" class="inputButton" id="sendNewSms" value=" i agree to the terms and conditions " />

<input type="checkbox"  onchange="document.getElementById('sendNewSms').disabled = !this.checked;" />