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

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>

javascript

Solution 1:^[1]

The following should work if your HTML code contains an element with the property id="fkWynik"

function mat_WypiszLiczbyNaturalne() {
  var elem = document.getElementById('fkEdit');
  if(!elem) {
    console.error("No element with id 'fkEdit' in the page.");
    return;
  }

  var T = elem.value;
  var value = "";

  if (T && !isNaN(Number(T))) { // if T not null, not empty, not undefined, not 0 and is a number
    var S = "";
    for (var I = 1; I < Number(T) + 1; I++) {
      S = S + ", " + I.toString();
    }
    value = S.substr(2) + " = ";
  } else {
    value = "Prosz? wprowadzi? liczb?!";
  }

  console.log("value: " + value);  
  document.getElementById('fkWynik').value = value;
}

mat_WypiszLiczbyNaturalne();

Sources

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Source: Stack Overflow

Solution	Source
Solution 1	lezhumain

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

Solution 1:[1]

Sources

Related Questions

Solution 1:^[1]