Javascript jQuery onchange 选择选项
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/7806855/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
jQuery onchange select option
提问by Manuel van Rijn
Let's say I have this HTML:
假设我有这个 HTML：
<select id='list'>
<option value='1'>First</option>
<option value='2'>Second</option>
<option value='3'>Third </option>
</select>
<input type ="text" id="text"/>
and then this JavaScript
然后这个 JavaScript
//other variables are also declared here
var x1 = 5;
var x2 = 10;
var value = x1 * x2;
var list_value =$("#list").change(function() {
$(this).val();
// just an example of how i want the function in the variable
});
var nwval = value * list_value;
$('#text').val(nwval);
// some long piece of code
// i'm also using the list_value value somewhere in the long piece of code..
I want the val in the textbox to change as the user selects an option, I know it'll work if I wrap the change event around it, but is there any way to go about this while keeping it as that variable list_value?
我希望文本框中的 val 在用户选择一个选项时发生变化，我知道如果我将更改事件包装在它周围它会起作用，但是有什么办法可以做到这一点，同时保持它作为该变量list_value？
回答by Manuel van Rijn
var x1 = 5;
var x2 = 10;
var value = x1 * x2;
var nwval;
$("#list").change(function() {
nwval = value * $(this).val();
$('#text').val(nwval);
});
回答by Sedat Ba?ar
$('#text').val($('option:selected').text());
$('#list').change(function(){
$('#text').val($('option:selected').text());
})
check from here http://jsfiddle.net/QrHUN/
回答by Hailwood
Wrapping the change event is the better way as it creates a closure, you could use global variables as below, but you would be better (imho) to simply grab the value again futher down.
包装更改事件是更好的方法，因为它创建了一个闭包，您可以使用如下全局变量，但您最好（恕我直言）简单地再次获取该值。
You could technically do (although a bad idea as it is global variables):
从技术上讲，您可以这样做（尽管这是一个坏主意，因为它是全局变量）：
var x1 = 5;
var x2 = 10;
var value = x1 * x2;
var list_value = 1;
$("#list").change(function() {
list_value = $(this).val();
var nwval = value * list_value;
$('#text').val(nwval);
});
回答by epascarello
this returns a jQuery object, not a value.
这将返回一个 jQuery 对象，而不是一个值。
var list_value =$("#list").change(function() {
If you want the value outside of the code, you would need to do something like this
如果你想要代码之外的值，你需要做这样的事情
var list_value = 0;
var sel = $("#list").change(function() {
list_value = $(this).val();
}).change();
var nwval = value * list_value;
$('#text').val(nwval);
BUT the onchange event will never update the page, just that variable!
但是 onchange 事件永远不会更新页面，只会更新那个变量！
