Dropdownlist可输入，可选择的方法

 function addTxtTanto(va){
    document.all("txtTitle").value=va; document.all("txtTitle").select();
}
function checktitle(){
    var drp = document.all("DDLTitle");
    var t=document.all("txtTitle");
    var j=0;
    if(t.value==""){
     }else{ 
            for(var i=0;i<drp.length;i++){
                  if(t.value==drp.options(i).text){
                       drp.value=drp.options(i).value;
                       break;
                  }else{
                       j=j+1;
                  }
             }
             if(j==drp.length){
              t.value="";
              t.select();
              alert("タイトルが存在していません。");
             }
      }
}

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