Question

In this code, I am creating number of Decoder outputs (D1,D2,D3…) depending on Decoder Type (4×1, 8×1, 16x) in the truth table.

If the Decoder Type is 4×1 I create 4x outputs 4*(D0,D1,D2,D3) for 4 different Decoders.

If the Decoder Type is 8×1 I create 2x outputs 2*(D0,D1,D2,D3,D4,D5,D6,D7) for 2 different Decoders.

If the Decoder Type is 16×1 I create 1x outputs 1*(D0,D1,D2,D3,D4,D5,D6,D7,...,D15) for 1 Decoder.

Now to make it easy for the user to distinguish between the various decoders, I would like to put the decoder name ontop of the corresponding Decoderoutputs. For example When I have 4×1 decoders, how can I put headers Decoder1, Decoder2, Decoder3, Decoder4 on top of (D0,D1,D2,D3)(D0,D1,D2,D3)(D0,D1,D2,D3)(D0,D1,D2,D3)?

P.S. In the code you can change the decodertype to 8x1 or 16x1. It’s defined as follows:

var decoderType="4x1";

Answer 1

The idea is to use colspan property of td tag. You should add the following code to generateTruthTableHTML function:

text += "<th class='th' colspan="+VariableCount+">Variable</td>";
for(var k = 0; k < counter; k++) {
  var count = Math.pow(2,VariableNames.length) /counter;
  text += "<th class='th' colspan=" + count + ">Decoder&nbsp;" +
          (k+1) + "</th>";
}    
text += "</tr><tr>";

Edited fiddle