How to Get the Value of a Dropdown Before It Changes in jQuery?-JS Tutorial-php.cn

Obtaining Dropdown Value Before Change

In jQuery, the change event is often used to capture the value of a dropdown when it is modified. However, this event only provides the value after the change has occurred. To obtain the value of the dropdown before the change, a different approach is necessary.

One solution involves combining the focus and change events. When the dropdown receives focus, the current value can be stored in a variable. When the change event occurs, this stored value can be used to determine the value before the change.

Here's how you can implement this solution:

(function () { var previous;

$("select").on('focus', function () { // Store the current value on focus and on change previous = this.value; }).change(function() { // Do something with the previous value after the change alert(previous);

// Make sure the previous value is updated previous = this.value; }); })(); Copy after login In this script:

The focus event listener stores the current value of the dropdown in the previous variable. The change event listener executes an action that utilizes the previous value, such as displaying it in an alert box. The previous variable is then updated to the new value of the dropdown. This approach allows you to capture the value of the dropdown before it changes. Keep in mind that this technique should be applied to all elements on the page that require this functionality. Additionally, if the elements are inserted dynamically, the event listeners must be bound after the elements are added to the DOM.

A live example of this solution can be found at the following URL: http://jsfiddle.net/x5PKf/766.