demo/visibletabs.html

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <title>CodeMirror: Visible tabs demo</title>
    <link rel="stylesheet" href="../lib/codemirror.css">
    <script src="../lib/codemirror.js"></script>
    <script src="../mode/clike/clike.js"></script>
    <link rel="stylesheet" href="../doc/docs.css">

    <style type="text/css">
      .CodeMirror {border-top: 1px solid #eee; border-bottom: 1px solid #eee;}
      .cm-tab {
         background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADAAAAAMCAYAAAAkuj5RAAAAAXNSR0IArs4c6QAAAGFJREFUSMft1LsRQFAQheHPowAKoACx3IgEKtaEHujDjORSgWTH/ZOdnZOcM/sgk/kFFWY0qV8foQwS4MKBCS3qR6ixBJvElOobYAtivseIE120FaowJPN75GMu8j/LfMwNjh4HUpwg4LUAAAAASUVORK5CYII=);
         background-position: right;
         background-repeat: no-repeat;
      }
    </style>
  </head>
  <body>
    <h1>CodeMirror: Visible tabs demo</h1>

    <form><textarea id="code" name="code">
#include "syscalls.h"
/* getchar:  simple buffered version */
int getchar(void)
{
	static char buf[BUFSIZ];
	static char *bufp = buf;
	static int n = 0;
	if (n == 0) {  /* buffer is empty */
		n = read(0, buf, sizeof buf);
		bufp = buf;
	}
	return (--n >= 0) ? (unsigned char) *bufp++ : EOF;
}
</textarea></form>

<p>Tabs inside the editor are spans with the
class <code>cm-tab</code>, and can be styled.

    <script>
      var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
        lineNumbers: true,
        tabSize: 4,
        indentUnit: 4,
        indentWithTabs: true,
        mode: "text/x-csrc"
      });
    </script>

  </body>
</html>