Home/ Questions/Q 7541001
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-30T07:46:52+00:00

I have a table in a cell that displays the numbers a user enters

  • 0

I have a table in a cell that displays the numbers a user enters with buttons (using onclick and a showthis function. I need to be able to store the value as a variable in order to perform operations on it. How can I do this?
PS: I am using JavaScript and HTML

<script language="JavaScript" type="text/javascript"> 
    function showthis(first){ 
        document.getElementById("displaycell").innerHTML+=first; 
    } 
</script>
<body> 
  <h1 align="center"> RPN Calculator </h1>
  <table summary align="center" border="1" cellpadding="1" cellspacing="3">
    <tr>
      <th id="displaycell" colspan="5" type="text"> </td>
    </tr>
    <tr>
      <td>
        <button type="button" onclick="showthis('1')">1</button>
      </td>
      <td>
        <button type="button" onclick="showthis('2')">2</button>
      </td>
      <td>
        <button type="button" onclick="showthis('3')">3</button>
     </td>
     <!-- ... -->
Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Firstly you should not be using += with innerHTML. It means that you will end up with the numbers appending to the cell’s internal value rather than overwriting it.

    function showthis ( number ) {
    var cell = document.getElementById('displaycell');
    cell.innerHTML = "";
    cell.appendChild( document.createTextNode( number ));
}

    Would be a much better way to handle that.

    Next, within showthis you are best off storing the value in a variable so that you can access it directly from javascript in the future.

    var displayStore = 0;

function showthis ( number ) {
    var cell = document.getElementById('displaycell');
    cell.innerHTML = "";
    cell.appendChild( document.createTextNode( number ));

    // you can either do this in a variable local to the <td> DOM Object like so
    cell.currentDisplayNumber = number;

    //or in a global variable like so
    displayStore = number;
}

    Finally, to access that variable again you can either read it out of the displaystore <td> or read it from your variable.

    function DoStuff0 () {
    var number = Number( document.getElementById( 'displaycell' )).innerHTML;
    // rest
}

function DoStuff1 () {
    var number = document.getElementById('displaycell').currentDisplayNumber;
    // rest
} 

function DoStuff2 () {
    var number = displayStore;
    // rest
}
    • 0