我创建了一个下拉菜单。像这样,下拉列表将 1
显示为下拉列表中的默认值,但我还想显示在我首先选择任何内容之前分配给该显示的值。这意味着,在我单击任何内容之前,我希望它默认显示“您选择了:一个”。我怎样才能最好地做到这一点?
function myFunction() {
var x = document.getElementById("mySelect").value;
if (x == "one") {
document.getElementById("demo").innerHTML = "You selected: " + x;
} else if (x == "two") {
document.getElementById("demo").innerHTML = "You selected: " + x;
} else if (x == "three") {
document.getElementById("demo").innerHTML = "You selected: " + x;
}
}
<select name="test" id="mySelect" onchange="myFunction()">
<option value="one">1</option>
<option value="two">2</option>
<option value="three">3</option>
</select>
<p id="demo"></p>
谢谢!
最佳答案
只需调用myFunction()
onload
function myFunction() {
var x = document.getElementById("mySelect").value;
if (x == "one") {
document.getElementById("demo").innerHTML = "You selected: " + x;
} else if (x == "two") {
document.getElementById("demo").innerHTML = "You selected: " + x;
} else if (x == "three") {
document.getElementById("demo").innerHTML = "You selected: " + x;
}
}
myFunction(); // call onload
<select name="test" id="mySelect" onchange="myFunction()">
<option value="one">1</option>
<option value="two">2</option>
<option value="three">3</option>
</select>
<p id="demo"></p>
更新删除 if
语句
function myFunction() {
var x = document.getElementById("mySelect").value;
document.getElementById("demo").innerHTML = "You selected: " + x;
}
myFunction(); // call onload
<select name="test" id="mySelect" onchange="myFunction()">
<option value="one">1</option>
<option value="two">2</option>
<option value="three">3</option>
</select>
<p id="demo"></p>
关于javascript - 使用 HTML 下拉列表显示默认值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60447880/