Converting Binary to text using JavaScript

How can I convert Binary code to text using JavaScript? I have already made it convert text to binary but is there a way of doing it the other way around?

Here is my code:

function convertBinary() {
  var output = document.getElementById("outputBinary");
  var input = document.getElementById("inputBinary").value;
  output.value = "";
  for (i = 0; i < input.length; i++) {
    var e = input[i].charCodeAt(0);
    var s = "";
    do {
      var a = e % 2;
      e = (e - a) / 2;
      s = a + s;
    } while (e != 0);
    while (s.length < 8) {
      s = "0" + s;
    }
    output.value += s;
  }
}

<div class="container">
  <span class="main">Binary Converter</span><br>
  <textarea autofocus class="inputBinary" id="inputBinary" onKeyUp="convertBinary()"></textarea>
  <textarea class="outputBinary" id="outputBinary" readonly></textarea>
  <div class="about">Made by <strong>Omar</strong></div>
</div>

Answer

Use toString(2) to convert to a binary string. For example:

var input = document.getElementById("inputDecimal").value;
document.getElementById("outputBinary").value = parseInt(input).toString(2);

or parseInt(input,10) if you know the input should be decimal. Otherwise input of “0x42” will be parsed as hex rather than decimal.

EDIT: Just re-read the question. To go from binary to text, use parseInt(input,2).toString(10).

Everything above is for numbers only. E.g., 4 <-> 0100. If you want 4 <-> decimal 52 (its ASCII value), use String.fromCharCode() (see this answer).

EDIT 2: per request for where everything fits, try this:

function BinToText() {
    var input = document.getElementById("inputBinary").value;
    document.getElementById("outputText").value = parseInt(input,2).toString(10);
}
...
<textarea autofocus class="inputBinary" id="inputBinary" onKeyUp="BinToText()"></textarea>
<textarea class="outputBinary" id="outputText" readonly></textarea>

If you put 0100 in inputBinary, you should get 4 in outputText (not tested).