Textarea Code Editor With Syntax Highlighting

This code creates a dynamic code editor with a sleek design. The major functionality includes syntax highlighting, resizable textarea, and tab indentation. It empowers you to write and edit code effortlessly. The editor’s toolbar offers options for indentation preferences and fullscreen mode, enhancing your coding experience. With syntax highlighting powered by the popular highlight.js library, your code becomes more readable. Whether you’re a seasoned developer or just starting, this code editor is here to elevate your coding journey.

How to Create Textarea Code Editor With Syntax Highlighting

1. First of all, load the following assets into the head tag of your HTML document.

<link rel='stylesheet' href='https://cdn.jsdelivr.net/foundation/6.2.0/foundation.min.css'>

2. Create an HTML file and include a textarea element with the class “editor” to serve as your code input space. Add a <code> element where your highlighted code will be displayed.

<div class="editor-holder">
	<ul class="toolbar">
		<li><a href="#" id="indent" title="Toggle tabs or spaces"><i class="fa fa-indent"></i></a></li>
		<li><a href="#" id="fullscreen" title="Toggle fullscreen mode"><i class="fa fa-expand"></i></a></li>
	</ul>
	<div class="scroller">
		<textarea class="editor allow-tabs">&lt;div class="Editable Textarea"&gt;
  &lt;h1&gt;This is a fully editable textarea which auto highlights syntax.&lt;/h1&gt;
  &lt;p&gt;Type or paste any code in here...&lt;/p&gt;
&lt;div&gt;

&lt;?php
  var simple = "coding";
?&gt;

&lt;script&gt;
  with = "Tab or double space functionality";
&lt;/script&gt;</textarea>
		<pre><code class="syntax-highight html"></code></pre>
	</div>
</div>

3. Style using the following CSS styles:

body {
  margin: 0;
  padding: 0;
  height: 100%;
  width: 100%;
  position: relative;
  background: #72c3c3 !important;
}

.editor-holder {
  width: 800px;
  height: 500px;
  margin-top: 50px;
  border-radius: 3px;
  position: relative;
  top: 0;
  background: #1f1f1f !important;
  overflow: auto;
  box-shadow: 5px 5px 10px 0px rgba(0, 0, 0, 0.4);
  transition: all 0.5s ease-in-out;
}
.editor-holder.fullscreen {
  width: 100%;
  height: 100%;
  margin: 0;
  left: 0;
}
.editor-holder .toolbar {
  width: 100%;
  list-style: none;
  position: absolute;
  top: -2px;
  margin: 0;
  left: 0;
  z-index: 3;
  padding: 8px;
  background: #afafaf;
}
.editor-holder .toolbar li {
  display: inline-block;
}
.editor-holder .toolbar a {
  line-height: 20px;
  background: rgba(144, 144, 144, 0.6);
  color: grey;
  box-shadow: inset -1px -1px 1px 0px rgba(0, 0, 0, 0.28);
  display: block;
  border-radius: 3px;
  cursor: pointer;
}
.editor-holder .toolbar a:hover {
  background: rgba(144, 144, 144, 0.8);
}
.editor-holder .toolbar a.active {
  background: rgba(144, 144, 144, 0.8);
  box-shadow: none;
}
.editor-holder .toolbar i {
  color: #565656;
  padding: 8px;
}
.editor-holder textarea, .editor-holder code {
  width: 100%;
  height: auto;
  min-height: 450px;
  font-size: 14px;
  border: 0;
  margin: 0;
  top: 46px;
  left: 0;
  padding: 20px !important;
  line-height: 21px;
  position: absolute;
  font-family: Consolas, Liberation Mono, Courier, monospace;
  overflow: visible;
  transition: all 0.5s ease-in-out;
}
.editor-holder textarea {
  background: transparent !important;
  z-index: 2;
  height: auto;
  resize: none;
  color: #fff;
  text-shadow: 0px 0px 0px rgba(0, 0, 0, 0);
  text-fill-color: transparent;
  -webkit-text-fill-color: transparent;
}
.editor-holder textarea::-webkit-input-placeholder {
  color: white;
}
.editor-holder textarea:focus {
  outline: 0;
  border: 0;
  box-shadow: none;
}
.editor-holder code {
  z-index: 1;
}

pre {
  white-space: pre-wrap;
  white-space: -moz-pre-wrap;
  white-space: -pre-wrap;
  white-space: -o-pre-wrap;
  word-wrap: break-word;
}
pre code {
  background: #1f1f1f !important;
  color: #adadad;
}
pre code .hljs {
  color: #a9b7c6;
  background: #282b2e;
  display: block;
  overflow-x: auto;
  padding: 0.5em;
}
pre code .hljs-number,
pre code .hljs-literal,
pre code .hljs-symbol,
pre code .hljs-bullet {
  color: #6897BB;
}
pre code .hljs-keyword,
pre code .hljs-selector-tag,
pre code .hljs-deletion {
  color: #cc7832;
}
pre code .hljs-variable,
pre code .hljs-template-variable,
pre code .hljs-link {
  color: #629755;
}
pre code .hljs-comment,
pre code .hljs-quote {
  color: #808080;
}
pre code .hljs-meta {
  color: #bbb529;
}
pre code .hljs-string,
pre code .hljs-attribute,
pre code .hljs-addition {
  color: #6A8759;
}
pre code .hljs-section,
pre code .hljs-title,
pre code .hljs-type {
  color: #ffc66d;
}
pre code .hljs-name,
pre code .hljs-selector-id,
pre code .hljs-selector-class {
  color: #e8bf6a;
}
pre code .hljs-emphasis {
  font-style: italic;
}
pre code .hljs-strong {
  font-weight: bold;
}

4. Load the jQuery, Font Awesome Icons Kit, Emmet JS and Highlight JS by adding the following CDN links before closing the body tag:

<script src='https://code.jquery.com/jquery-2.2.4.min.js'></script>
<script src='https://use.fontawesome.com/b2c0f76220.js'></script>
<script src='https://raw.githubusercontent.com/emmetio/textarea/master/emmet.min.js'></script>
<script src='//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.5.0/highlight.min.js'></script>

5. Finally, add the following JavaScript function to activate the code editor:

var tabCharacter = "  ";
var tabOffset = 2;

$(document).on('click', '#indent', function(e){
	e.preventDefault();
	var self = $(this);
	
	self.toggleClass('active');
	
	if(self.hasClass('active'))
	{
		tabCharacter = "\t";
		tabOffset = 1;
	}
	else
	{
		tabCharacter = "  ";
		tabOffset = 2;
	}
})

$(document).on('click', '#fullscreen', function(e){
	e.preventDefault();
	var self = $(this);
	
	self.toggleClass('active');
	self.parents('.editor-holder').toggleClass('fullscreen');
});

/*------------------------------------------
	Render existing code
------------------------------------------*/
$(document).on('ready', function(){
	hightlightSyntax();
	
	emmet.require('textarea').setup({
    pretty_break: true,
    use_tab: true
	});
});




/*------------------------------------------
	Capture text updates
------------------------------------------*/
$(document).on('ready load keyup keydown change', '.editor', function(){
	correctTextareaHight(this);
	hightlightSyntax();
});


/*------------------------------------------
	Resize textarea based on content  
------------------------------------------*/
function correctTextareaHight(element)
{
  var self = $(element),
      outerHeight = self.outerHeight(),
      innerHeight = self.prop('scrollHeight'),
      borderTop = parseFloat(self.css("borderTopWidth")),
      borderBottom = parseFloat(self.css("borderBottomWidth")),
      combinedScrollHeight = innerHeight + borderTop + borderBottom;
  
  if(outerHeight < combinedScrollHeight )
  {
    self.height(combinedScrollHeight);
  }
}
// function correctTextareaHight(element){
// 	while($(element).outerHeight() < element.scrollHeight + parseFloat($(element).css("borderTopWidth")) + parseFloat($(element).css("borderBottomWidth"))) {
// 		$(element).height($(element).height()+1);
// 	};
// }


/*------------------------------------------
	Run syntax hightlighter  
------------------------------------------*/
function hightlightSyntax(){
	var me  = $('.editor');
	var content = me.val();
	var codeHolder = $('code');
	var escaped = escapeHtml(content);
	
	codeHolder.html(escaped);
	
	$('.syntax-highight').each(function(i, block) {
		hljs.highlightBlock(block);
	});
}


/*------------------------------------------
	String html characters
------------------------------------------*/
function escapeHtml(unsafe) {
	return unsafe
			 .replace(/&/g, "&amp;")
			 .replace(/</g, "&lt;")
			 .replace(/>/g, "&gt;")
			 .replace(/"/g, "&quot;")
			 .replace(/'/g, "&#039;");
}


/*------------------------------------------
	Enable tabs in textarea
------------------------------------------*/
$(document).delegate('.allow-tabs', 'keydown', function(e) {
	var keyCode = e.keyCode || e.which;

	if (keyCode == 9) {
		e.preventDefault();
		var start = $(this).get(0).selectionStart;
		var end = $(this).get(0).selectionEnd;

		// set textarea value to: text before caret + tab + text after caret
		$(this).val($(this).val().substring(0, start)
								+ tabCharacter
								+ $(this).val().substring(end));

		// put caret at right position again
		$(this).get(0).selectionStart =
		$(this).get(0).selectionEnd = start + tabOffset;
	}
});

That’s all! hopefully, you have successfully created Textarea Code Editor With Syntax Highlighting. If you have any questions or suggestions, feel free to comment below.

Asif Mughal

I code and create web elements for amazing people around the world. I like work with new people. New people new Experiences.
I truly enjoy what I’m doing, which makes me more passionate about web development and coding. I am always ready to do challenging tasks whether it is about creating a custom CMS from scratch or customizing an existing system.