Javawscript Three Level menu implementation principle _javascript Skill

Provinces:	Please selectShandong Province
City:	= = Please select = =WeihaiDezhouBinzhou
District:	= = Please select township = =WeihaiWendengRongchengRushan

Provinces, cities, counties Data Structures: "Name, parent class ID, current ID"

Onchange= "Changelocation2 (document.editform.smalllocation.options[ Document.editform.smalllocation.selectedindex].value) "

According to SelectedIndex, get the parent class ID of the next level associated menu,

Copy Code code as follows:

function Changelocation (LocationID)
{
document.editForm.smalllocation.length = 0;
document.editForm.dlmc0.length = 0;
document.getElementById ("Dlmc0"). length=0;
Document.editform.dlmc0.options[0] = new Option (' = = Please select = = ', ');
document.getElementById ("Dlmc0"). Options[0] = new Option (' = = Please select = = ', ');

alert (LocationID);
var Locationid=locationid;
var i;
Document.editform.smalllocation.options[0] = new Option (' = = Please select = = ', ');
For (I=0;i < onecount; i++)
{
if (subcat[i][1] = = LocationID)
{
Document.editform.smalllocation.options[document.editform.smalllocation.length] = new Option (subcat[i][0], subcat[ I][2]);
}
}
}