JavaScript通过this变量快速找出用户选中radio按钮的方法

<script>function favAnimal(button) {alert('You like '+button.value+'s.');}</script><input type="radio" name="marsupial" value="kangaroo"    onchange="favAnimal(this)">Kangaroo<br /><input type="radio" name="marsupial" value="Opossum"    onchange="favAnimal(this)">Opossum<br /><input type="radio" name="marsupial" value="Tasmanian Tiger"    onchange="favAnimal(this)">Tasmanian Tiger