jQuery onchange选择选项

11 javascript jquery

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"/>
Run Code Online (Sandbox Code Playgroud)

然后是这个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..
Run Code Online (Sandbox Code Playgroud)

我希望文本框中的val能够随着用户选择一个选项而改变,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将它保持为变量list_value吗?

Man*_*ijn 16

var x1 = 5;
var x2 = 10;
var value = x1 * x2;
var nwval;
$("#list").change(function() {
    nwval = value * $(this).val();
    $('#text').val(nwval);
});
Run Code Online (Sandbox Code Playgroud)