js 判斷多個控件的值不能相同

function validfn(){
    var codeArr = [1,2,3,4,5,1,2];
    for( var k = 0; k < codeArr.length; k ++ ){
        for( var j = k+1; j < codeArr.length; j ++ ){
           if( codeArr[k] == codeArr[j]){
               return showAlertInfo("fail","不能有重複的類型傾向");
           }
        }   
    }
    return true;
}