Hi I'm trying to make a website. But I need to make a syntax highlighting program that Categorize commands based on what they do. For example, when i type a code in C/C++ or Java on my site, the colors will become highlighted instantly. One group would be I/O, another one would be Control commands. And I want would color the text based off of what type of command it is(such as green for the control commands and red for the I/O). Please I need help.

function change() {
  document.getElementsByClassName('io')[0].style.color = 'red';
  document.getElementsByClassName('control-commands')[0].style.color = 'green';
<div class='io'>IO</div>
<div class='control-commands'>Control Commands</div>
<br />
<button onclick="change()">Change</button>

I don't really understand the question, but if you mean you want to display code with syntax highlighting (rather than edit it, in which case rproffitt's answer is correct), then there are a few libraries for this, namely rainbow and highlight.js.