function etoa(e) {
  result = '';
  if (e.Emode == 0) {
    result = etoa(e.sides[0])+' '+e.sign+' '+etoa(e.sides[1]);
  } else if (e.iscomplex) {
    result = '('+etoa(e.value[0])+' '+e.value[1]+' '+etoa(e.value[2])+')';
  } else {
    if (e.unit) {
      if (e.value == '1' || e.value == 1) {
        result = e.unit;
      } else {
        result = e.value+e.unit;
      }
    } else {
      result = e.value+e.unit;
    }
  }
  return result;
}
// works, output:
//// ((a * x) + b) = 0



function etohtml(e) {
  result = '';
  if (e.Emode == 0) {
    result = '<span class="equation">'+etohtml(e.sides[0])+' '+e.sign+' '+etohtml(e.sides[1])+'</span>';
  } else if (e.iscomplex) {
    result = '<span class="led">'+etohtml(e.value[0])+' '+e.value[1]+' '+etohtml(e.value[2])+'</span>';
  } else {
    result = '<span class="number">'+etoa(e)+'</span>';
  }
  return result;
}
// this one works - output:
// <span class="equation"><span class="led"><span class="led"><span class="number">a</span> * <span class="number">x</span></span> + <span class="number">b</span></span> = <span class="number">0</span></span>


function etodom(e) {
  if (e.Emode == 0) {
    result = document.createElement('span');
    try {result.className = 'equation';}
    catch (err) {result.class = 'equation';}
    result.appendChild(etodom(e.sides[0]));
    result.appendChild(document.createTextNode(' '+e.sign+' '));
    result.appendChild(etodom(e.sides[1]));
  } else if (e.iscomplex) {
    result = document.createElement('span');
    try {result.className = 'led';}
    catch (err) {result.class = 'led';}
    result.appendChild(etodom(e.value[0])); // Error here:
      // uncaught exception: [Exception... "Could not convert JavaScript
      // argument" nsresult: "0x80570009 (NS_ERROR_XPC_BAD_CONVERT_JS)" location:
      // "JS frame :: file:///H:/home/work/equations.html :: etodom :: line 124" data: no]
    result.appendChild(document.createTextNode(' '+e.value[1]+' '));
    result.appendChild(etodom(e.value[2]));
  } else {
    result = document.createElement('span');
    try {result.className = 'number';}
    catch (err) {result.class = 'number';}
    result.appendChild(document.createTextNode(etoa(e)));
  }
  return result;
}