其實是個彙總
(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;
});
})();
https://stackoverflow.com/questions/4076770/getting-value-of-select-dropdown-before-change
https://stackoverflow.com/questions/18868867/jquery-chosen-before-change-event