Drop-down list

A drop-down list (also drop-down list) or drop-down list box (from english to drop down, fall down ') is a control of a graphical user interface with which a user can select a value from a predefined list of values. In the ground state while a read-only text box displays matched with one of the height of the text field button. Through a user action, such as a mouse click or a keyboard shortcut, works on a list of values ​​up or down.

Is not the text box read only, so also values ​​from the keyboard can be entered, this is called a combo box or a combo box. The similar behavior in the drop-down menu is used in contrast to select a submenu or command in a menu bar of a program or to select a hyperlink on a Web page.

Scope

Drop-down lists are primarily used where a list box would take an inordinate amount of space in a window.

Function

If an application window or a web page opened for the first time with a drop-down list, the displayed text field can contain either no or specified by the program or default page. In the drop down after a user action, not initially visible list the user can select one of the predefined values ​​. This or any of its linked value is displayed in the text box and accepted as the current value in the further processing.

Just as a list box can also be designed in the drop down list in multiple columns. This is useful if an explanation of the respective value is to be made ​​available, for example, in another column, or, if multiple data -communicating facilitate the selection of the desired value, or even possible at all. In programs also values ​​from a defined column as invisible to current values ​​can be the control. On websites this is not possible to HTML5.

For extensive lists the size of the list to a specific number can be limited. The navigation in the list is then supported by scroll bars.

Examples

Through a user action, the selection list of a dropdown list is visible.

Drop-down lists in HTML

Drop-down lists are defined with the HTML element In HTML, the individual selection items on the list with tags.

Selection of points can be divided with the

- day groups, but only one subdivision level is permitted. With such a simple tree structure, for example, navigation menus can be shown to save space on websites. As with the - day grouped selection points displayed depends on the Web browser: Some browsers, they represent a drop-down menu submenus with fold out, other than a subdivided drop-down list with group headers and slightly indented selection points.

GUI widget Scrollbar

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