Js How do I add up all numbers into one variable and show it?

February 3, 2022

Whenever I try doing the code myself, nothing shows up after I run the function, I’m wanting to add all the numbers from ‘fkWynik’.

function mat_WypiszLiczbyNaturalne() {
  var T = "";
  T = document.getElementById('fkEdit').value;
  if ((T.trim() != "") && (Number(T) > 0)) {
    var S = "";
    for (var I = 1; I < Number(T) + 1; I++) {
      S = S + ", " + I.toString();
    }
    document.getElementById('fkWynik').value = S.substr(2) + " = ";

  } else {
    document.getElementById('fkWynik').value = "Prosze wprowadzic liczbe!";
  }
}

<html>
<body>
   <FORM NAME="formularz1" ACTION=""> 
     <TABLE BORDER="0"> 
                    &nbsp;<INPUT TYPE="number" ID="fkEdit" STYLE="height:24px; width:55px;"> 
                    &nbsp;<INPUT TYPE="button" ID="fkWykonaj" VALUE="Wykonaj" onClick="mat_WypiszLiczbyNaturalne();">&nbsp;</TD> 
            </TR> 
            <TR><TD>&nbsp;<INPUT TYPE="text" ID="fkWynik" STYLE="width:545px; height:24px;" READONLY>&nbsp;</TD></TR> 
     </TABLE> 
   </FORM> 
</body>
</html>

>Solution :

You need to add the numbers together and concat it to the string:

    function mat_WypiszLiczbyNaturalne() {
      var T = "";
      T = document.getElementById('fkEdit').value;
      if ((T.trim() != "") && (Number(T) > 0)) {
        var S = "";
        var total = 0 
        for (var I = 1; I < Number(T) + 1; I++) {
          S = S + ", " + I.toString();
          total += I;
        }
        document.getElementById('fkWynik').value = S.substr(2) + " = "+total.toString();
    
      } else {
        document.getElementById('fkWynik').value = "Prosze wprowadzic liczbe!";
      }
    }

<html>
<body>
   <FORM NAME="formularz1" ACTION=""> 
     <TABLE BORDER="0"> 
                    &nbsp;<INPUT TYPE="number" ID="fkEdit" STYLE="height:24px; width:55px;"> 
                    &nbsp;<INPUT TYPE="button" ID="fkWykonaj" VALUE="Wykonaj" onClick="mat_WypiszLiczbyNaturalne();">&nbsp;</TD> 
            </TR> 
            <TR><TD>&nbsp;<INPUT TYPE="text" ID="fkWynik" STYLE="width:545px; height:24px;" READONLY>&nbsp;</TD></TR> 
     </TABLE> 
   </FORM> 
</body>
</html>