First of all, let me tell you the difference between combo box and list box:
Combo box includes the functions of list box and text box
Text box: only data can be entered
List box: only data can be selected
Combo box: can not only input data, but also select ``
Application background: There are two list boxes on the page, and the elements of one list box need to be moved to the other list box.
Basic idea of implementation:
(1) Write the init method to initialize the two list boxes;
(2) Add the onload event to the body to call the init method;
(3) Write move(s1,s2) to move the selected option in s1 to s2;
(4) Write moveAll(s1,s2) to move all options in s1 to s2.
(5) Add onclick event for button.
javascript code is as follows:
<script type="text/javascript" language="javascript"> //对下拉框信息进行初始化 function init() { for (i = ; i < ; i++) { var y = document.createElement("option");//增加一个元素option y.text = '选项' + i; var x=document.getElementById("s");//根据ID找到列表框 x.add(y, null); // } } //把选中的选项移到另一边 function move(s, s) { var index = s.selectedIndex; if (index == -) { alert("没有选中值"); return; } s.length++; s.options[s.length - ].value = s.options[index].value; s.options[s.length - ].text = s.options[index].text;//s中当前选中的值赋给s的最后一个元素 s.remove(index);//从s中移除当前元素 } //把一边的完全移到另一边 function moveAll(s, s) { if (s.length == ) { alert("没有可用选择"); return; } s.length = s.length + s.length; for (var i = ; i < s.length; i++) { s.options[s.length - s.length + i].value = s.options[i].value; s.options[s.length - s.length + i].text = s.options[i].text; } s.length = ; } </script>
Code:
<body onload="init()"> <table> <tr> <td><select id="s" size= style="width:"></select></td> <td><input type="button" name="moveToRight" value=">" onClick="move(s,s)"> <br> <br> <input type="button" name="moveAllToRight" value=">>" onClick="moveAll(s,s)"> <br> <input type="button" name="moveToLeft" value="<" onClick="move(s,s)"> <br> <br> <input type="button" name="moveAllToLeft" value="<<" onClick="moveAll(s,s)"></td> <td><select id="s" name="s" size= style="width:"></select></td> </tr> </table> </body>
The above content introduces you to the knowledge about how JavaScript can realize the moving effect of elements in the combo list box. I hope it will be helpful to you!