Return part of string after a certain character - javascript

Returns and outputs the text after the double colon character. By Hexodus http://stackoverflow.com/a/16470330/1600193

HTML

<p>
  <h5>Input:</h5>
  <strong id="my-input">Left Text:Right Text</strong>
  <h5>Output:</h5>
  <strong id="my-output">XXX</strong>
</p>

CSS

body {
  font-family: Calibri, sans-serif;
  color:#555;
}
h5 {
  margin-bottom: 0.8em;
}
strong {
  width:90%;
  padding: 0.5em 1em;
  background-color: cyan;
}
#my-output {
  background-color: gold;
}

JavaScript

var input_string = document.getElementById('my-input').innerText;
var output_element = document.getElementById('my-output');

var left_text = input_string.substring(0, input_string.indexOf(":"));

output_element.innerText = left_text;