选择元素的Click（鼠标按下）事件

Question

I have an empty select element, I want to execute some code when that element is clicked on, but I do not want the dropdown list to appear, here is what I have found:

1. When I disabled the select element I cannot catch the mousedown event.
2. When I enable the select element I can capture the mousedown event but the dropdown list appears.

For arguements sake what I want is to be able to click the select element, JavaScript to throw an alert box but I want to prevent the dropdown list from displaying.

Thanks!

Answer 1

capture onmousedown event of select element and cancel the event by setting event.returnValue to false.

<script type="text/javascript">
    function onSelectMouseDown() {
        event.returnValue = false;
        alert("mouse down caught and cancelled");
    }
</script>

<select id="select" onmousedown="onSelectMouseDown();"></select>

Answer 2

为什么不禁用select元素，然后将select元素包装在与select元素高度和宽度相同的div（或其他宽度）中，并在此div中使用mousedown事件？

Answer 3

<script>
function makeDisable(){
    var x=document.getElementById("mySelect")
    x.disabled=true
}
function makeEnable(){
    var x=document.getElementById("mySelect")
    x.disabled=false
}
function f() {
makeDisable();
alert("something");
t=setTimeout("makeEnable();",1);
}
</script>

<select id="mySelect" onMouseDown="f();">
  <option value="opt1">Option 1</option>
  <option value="opt2">Option 2</option>
</select>