在下拉列表中选择相同的值时触发事件? [英] Trigger the event when selected the same value in dropdown?
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问题描述
问题:我有一个下拉列表,其中有年份列表,但未选择任何内容,用户选择"1976",我运行一个函数.如果用户再次单击下拉菜单并再次选择"1976",我想再次运行该功能.
Issue: I have a dropdown with a list of years in it with nothing selected, the user selects "1976", I run a function. If the user clicks on the dropdown again and selects "1976" AGAIN, I want to run the function again.
$('select').on('change', function (e)
{
var optionSelected = $("option:selected", this);
var valueSelected = this.value;
alert(valueSelected);
});
推荐答案
Simple JS
---------
<html>
<head>
<script>
var prevIndex = "";
function onSelect()
{
var currIndex = document.getElementById("ddList").selectedIndex;
if( currIndex > 0 )
{
if( prevIndex != currIndex )
{
alert("Selected Index = " + currIndex);
prevIndex = currIndex;
}
else
{
prevIndex = "";
}
}
}
</script>
</head>
<body>
<select id="ddList" onClick="onSelect()">
<option value="0">Select Me</option>
<option value="1">List1</option>
<option value="2">List2</option>
<option value="3">List3</option>
</select>
</body>
</html>
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