javascript SELECT multiple

Specifies whether the browser should render the select element as a list box and allow users to make multiple selections from the list of options. By default, the size property is set to the number of nested option elements, but the value may be overridden with the size property setting. To change a scrolling pick list to a popup menu, set the multiple property to false and the size property to 1. Users can select contiguous items by Shift-clicking on the first and last items of the group. To make discontiguous selections, Windows users must Ctrl-click on each item; Mac users must Command-click on each item. The multiple property has no effect when size is set to 1 to display a popup menu.