从下拉列表中选择一个选项元素的文本值
问题描述：
给定一个HTML表单元素，如：
Given an HTML form element like:
<select id='mydropdown'>
<option value='foo'>Spam</option>
<option value='bar'>Eggs</option>
</select>
我知道我可以选择第一个选项与
I know I can select the first option with
document.getElementById("mydropdown").value='foo'
但是，假设我有一个值为垃圾邮件的变量;我可以通过其文本而不是其值来选择一个下拉项？
However, say I have a variable with the value "Spam"; can I select a dropdown item by its text rather than by its value?
答
var desiredValue = "eggs"
var el = document.getElementById("mydropdown");
for(var i=0; i<el.options.length; i++) {
if ( el.options[i].text == desiredValue ) {
el.selectedIndex = i;
break;
}
}