Specific implementation of the left and right movement effect of JS drop-down box content_javascript skills

Copy code The code is as follows:

< ;TITLE>Select drop-down menu

Select one or more items and click Add or Remove (press and hold Shift or ctrl can select multiple items), or double-click on the selection to add and remove.

Beijing Shanghai < option value="Shandong">Shandong Anhui Chongqing Fujian Gansu Guangdong Guangxi Guizhou Hainan Hebei Heilongjiang< ;/option>

Move up Move down

Value: