javascript联动

function citychange(obj){
    var prov = document.getElementById('prov');

    citysinfo.value = prov.value+obj.value;
}
function provchange(obj){
    var city = document.getElementById('city');
    var citysinfo = document.getElementById('citysinfo');

    // 只保留默认提示,其它多余的城市被删除
    city.options.length = 1;
    citysinfo.value = "";
    if(obj.selectedIndex>0){
        for(var i=0; i<citys[obj.selectedIndex-1].length; i++){
            var op = document.createElement('option');
            var txt = document.createTextNode(citys[obj.selectedIndex-1][i]);
            op.appendChild(txt);
            city.appendChild(op);
        }
        citysinfo.value = obj.value;
    }

}

window.onload=function(){
    var prov = document.getElementById('prov');

    for(var i=0; i<provs.length; i++){
        var op = document.createElement('option');
        var txt = document.createTextNode(provs[i]);
        op.appendChild(txt);
        prov.appendChild(op);
    }
}