javascript实现多级联动下拉菜单的方法

<SCRIPT LANGUAGE="JavaScript">

<!-- Begin

var arrItems1 = new Array();

var arrItemsGrp1 = new Array();

arrItems1[3] = "列二";

arrItemsGrp1[3] = 1;

arrItems1[4] = "列二三";

arrItemsGrp1[4] = 1;

arrItems1[5] = "列二四";

arrItemsGrp1[5] = 1;

arrItems1[6] = "列三";

arrItemsGrp1[6] = 2;

arrItems1[7] = "列三一";

arrItemsGrp1[7] = 2;

arrItems1[0] = "列四";

arrItemsGrp1[0] = 3;

arrItems1[1] = "列四一";

arrItemsGrp1[1] = 3;

arrItems1[2] = "列四二";

arrItemsGrp1[2] = 3;

var arrItems2 = new Array();

var arrItemsGrp2 = new Array();

arrItems2[21] = "列4-0";

arrItemsGrp2[21] = 0

arrItems2[22] = "列4-1";

arrItemsGrp2[22] = 0

arrItems2[31] = "列41-0";

arrItemsGrp2[31] = 1

arrItems2[34] = "列41-1";

arrItemsGrp2[34] = 1

arrItems2[35] = "列42-0";

arrItemsGrp2[35] = 2

arrItems2[99] = "列24-2";

arrItemsGrp2[99] = 5

arrItems2[100] = "列24-1";

arrItemsGrp2[100] = 5

arrItems2[57] = "列24-0";

arrItemsGrp2[57] = 5

arrItems2[101] = "列2-0";

arrItemsGrp2[101] = 3

arrItems2[102] = "列2-1";

arrItemsGrp2[102] = 3

arrItems2[103] = "列23-0";

arrItemsGrp2[103] = 4

arrItems2[104] = "列23-1";

arrItemsGrp2[104] = 4

arrItems2[105] = "列3-0";

arrItemsGrp2[105] = 6

arrItems2[106] = "列3-1";

arrItemsGrp2[106] = 6

arrItems2[200] = "列31-0";

arrItemsGrp2[200] = 7

arrItems2[201] = "列31-1";

arrItemsGrp2[201] = 7

arrItems2[203] = "列31-2";

arrItemsGrp2[203] = 7

function selectChange(control, controlToPopulate, ItemArray, GroupArray)

{

  var myEle ;

  var x ;

  // Empty the second drop down box of any choices

  for (var q=controlToPopulate.options.length;q>=0;q--) controlToPopulate.options[q]=null;

  if (control.name == "firstChoice") {

    // Empty the third drop down box of any choices

    for (var q=myChoices.thirdChoice.options.length;q>=0;q--) myChoices.thirdChoice.options[q] = null;

 }

  // ADD Default Choice - in case there are no values

  myEle = document.createElement_x("option") ;

  myEle.value = 0 ;

  myEle.text = "[列表]" ;

  controlToPopulate.add(myEle) ;

for ( x = 0 ; x < ItemArray.length  ; x++ )

    {

      if ( GroupArray[x] == control.value )

        {

          myEle = document.createElement_x("option") ;

          myEle.value = x ;

          myEle.text = ItemArray[x] ;

          controlToPopulate.add(myEle) ;

        }

    }

}

//  End -->

</script>

<form name=myChoices>

<table align="center">

<tr>

<td>

<SELECT id=firstChoice name=firstChoice onchange="selectChange(this, myChoices.secondChoice, arrItems1, arrItemsGrp1);">

  <option value="0">列表一</option>

  <option value="1">列表二</option>

  <option value="2">列表三</option>

  <option value="3">列表四</option>

</SELECT>

</TD><TD>

<SELECT id=secondChoice name=secondChoice onchange="selectChange(this, myChoices.thirdChoice, arrItems2, arrItemsGrp2);">

</SELECT>

<SELECT id=thirdChoice name=thirdChoice>

</SELECT>

</TD>

</TR>

</TABLE>

</form>