我希望用户可以通过单击ON(不透明度100%)或OFF(不透明度0%)而不是1或0来更改不透明度。这可能吗?代码:
<!DOCTYPE html>
<html>
<body>
<p id="p1">Change this phrase's opacity</p>
<select onchange="myFunction(this);" size="2">
<option>0 <!--I want this OFF not 0-->
<option selected="selected">1 <!--I want this ON not 1-->
</select>
<script>
function myFunction(x) {
var opacity = x.options[x.selectedIndex].text;
var el = document.getElementById("p1");
if (el.style.opacity !== undefined) {
el.style.opacity = opacity;
} else {
alert("Your browser doesn't support this!");
}
}
</script>
</body>
</html>
如果
可以将options
更改为具有值,则可以执行以下操作:
function myFunction(x) {
var opacity = x.options[x.selectedIndex].value;
var el = document.getElementById("p1");
if (el.style.opacity !== undefined) {
el.style.opacity = opacity;
} else {
alert("Your browser doesn't support this!");
}
}
<p id="p1">Change this phrase's opacity</p>
<select onchange="myFunction(this);" size="2">
<option value="0">OFF</option>
<option value="1" selected="selected">ON</option>
</select>