代码如下：
<SCRIPT LANGUAGE="JavaScript"> <!-- Begin var arrItems1 = new Array(); var arrItemsGrp1 = new Array(); arrItems1[3] = "Truck"; arrItemsGrp1[3] = 1; arrItems1[4] = "Train"; arrItemsGrp1[4] = 1; arrItems1[5] = "Car"; arrItemsGrp1[5] = 1; arrItems1[6] = "Boat"; arrItemsGrp1[6] = 2; arrItems1[7] = "Submarine"; arrItemsGrp1[7] = 2; arrItems1[0] = "Planes"; arrItemsGrp1[0] = 3; arrItems1[1] = "Ultralight"; arrItemsGrp1[1] = 3; arrItems1[2] = "Glider"; arrItemsGrp1[2] = 3; var arrItems2 = new Array(); var arrItemsGrp2 = new Array(); arrItems2[21] = "747"; arrItemsGrp2[21] = 0 arrItems2[22] = "Cessna"; arrItemsGrp2[22] = 0 arrItems2[31] = "Kolb Flyer"; arrItemsGrp2[31] = 1 arrItems2[34] = "Kitfox"; arrItemsGrp2[34] = 1 arrItems2[35] = "Schwietzer Glider"; arrItemsGrp2[35] = 2 arrItems2[99] = "Chevy Malibu"; arrItemsGrp2[99] = 5 arrItems2[100] = "Lincoln LS"; arrItemsGrp2[100] = 5 arrItems2[57] = "BMW Z3"; arrItemsGrp2[57] = 5 arrItems2[101] = "F-150"; arrItemsGrp2[101] = 3 arrItems2[102] = "Tahoe"; arrItemsGrp2[102] = 3 arrItems2[103] = "Freight Train"; arrItemsGrp2[103] = 4 arrItems2[104] = "Passenger Train"; arrItemsGrp2[104] = 4 arrItems2[105] = "Oil Tanker"; arrItemsGrp2[105] = 6 arrItems2[106] = "Fishing Boat"; arrItemsGrp2[106] = 6 arrItems2[200] = "Los Angelas Class"; arrItemsGrp2[200] = 7 arrItems2[201] = "Kilo Class"; arrItemsGrp2[201] = 7 arrItems2[203] = "Seawolf Class"; 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("option") ; myEle.value = 0 ; myEle.text = "[SELECT]" ; controlToPopulate.add(myEle) ; for ( x = 0 ; x < ItemArray.length ; x++ ) { if ( GroupArray[x] == control.value ) { myEle = document.createElement("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 SELECTED>[SELECT]</option> <option value=1>Land</option> <option value=2>Sea</option> <option value=3>Air</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>