获取表单select域的选择部分的文本

body>
<form action="index.php">
    <select name="" id="select">
        <option value="1">一</option>
        <option value="2">二</option>
        <option value="3">三</option>
    </select>
</form>
<script>
    window.onload=function () {
        var select=document.getElementById('select');
        select.onchange=function (ev) {
            console.log(this.options[this.selectedIndex].text);
        }
    }
</script>
</body>