ansi_up is a simple, easy to use library that provides a streaming API to transform text containing ANSI color escape codes into proper HTML. It can also transform any text that looks like a URL into an HTML anchor tag.
For example, turn this terminal output:
ESC[1;Foreground [1;30m 30 [1;30m 30 [1;30m 30 [1;30m 30 [1;30m 30 [1;30m 30 [1;30m 30 [1;30m 30 [0m [1;31m 31 [1;31m 31 [1;31m 31 [1;31m 31 [1;31m 31 [1;31m 31 [1;31m 31 [1;31m 31 [0m [1;32m 32 [1;32m 32 [1;32m 32 [1;32m 32 [1;32m 32 [1;32m 32 [1;32m 32 [1;32m 32 [0m ...
...into this browser output:
var AU = require('ansi_up');var ansi_up = new AU.default;var txt = "\n\n\033[1;33;40m 33;40 \033[1;33;41m 33;41 \033[1;33;42m 33;42 \033[1;33;43m 33;43 \033[1;33;44m 33;44 \033[1;33;45m 33;45 \033[1;33;46m 33;46 \033[1m\033[0\n\n\033[1;33;42m >> Tests OK\n\n"var html = ansi_up.ansi_to_html(txt);
More examples are in the 'examples' directory in the repo.
$ npm install ansi_up
Version 2.x is the latest stateful, streaming version of the API. It is simpler and more correct. Version 1.3.0 was the last of the older, deprecated API.
In order to use ansi_up, you must Instantiate an object using your given module system.
This replaces ANSI terminal escape codes with SPAN tags that wrap the content. See the example output above.
This function only interprets ANSI SGR (Select Graphic Rendition) codes that can be represented in HTML. For example, cursor movement codes are ignored and hidden from output.
The default style uses colors that are very close to the prescribed standard. The standard assumes that the text will have a black background. These colors are set as inline styles on the SPAN tags. Another option is to set 'use_classes: true' in the options argument. This will instead set classes on the spans so the colors can be set via CSS. The class names used are of the format
ansi-bright-*-fg/bg where * is the colour name, i.e black/red/green/yellow/blue/magenta/cyan/white. See the examples directory for a complete CSS theme for these classes.
This simply removes the ANSI escape codes from the stream. No escaping is done.
This replaces any links in the text with anchor tags that display the link. Only strings starting with 'http' or 'https', and surrounded by whitespace are considered valid patterns. You should only call this method if you can guarantee that the full URL will be passed into ansi_to_html(). If the URL is split along a buffer boundary, then the wrong URL will be 'linkified'.
This does the minimum escaping of text to make it compliant with HTML. In particular, the '&','<', and '>' characters are escaped.
This causes the SPAN tags to use class names for the color style instead of specified RGB values.
On a high level, ansi_up takes a stream of text and transforms it proper HTML with colors. It does this by buffering the data and performing multiple passes over the stream. Each time it consumes data, it may or may not emit HTML. This HTML will always be proper HTML.
Because this process requires buffering (ie. stateful), you must insantiate an ansi_up object in order to begin. Also, text may be received later that is styled by a previous.
The first pass converts characters that are unsafe for HTML into their equivalents. It will only convert '&', '<', and '>' characters. This pass is optional, and is on by default.
The second pass converts any ANSI color sequences to HTML spans. It does this by recognizing what is termed as ANSI SGR codes. All ANSI sequences (SGR and non-SGR) are removed from the output stream. The SGR codes create HTML SPAN tags to surround text that is styled by those codes. If the ANSI sequence is incomplete, it will be held in ansi_up's internal buffer until new data is received to complete it.
The third and final pass transforms URLs to HTML anchors. This will also buffer output until a non URL character is received. This pass is optional, and is off by default.
There are two ways to stream this data to a web page. A push model or a pull model.
I have personally used a pull model to 'tail' a file.
In my 'pull' model, I had a process generating a log file on a remote machine. I had a web server running on the same machine. I developed a simple page that used AJAX to poll the web server periodically. Specifically I used an HTTP/1.1 GET request with RFC 7233 Range query. The server would return either range response.
I would then process each chunk received with ansi_up, and append the new spans to the innerHTML of a PRE tag.
ansi_up should be called via the functions defined on the module. It is recommended that the HTML is rendered with a monospace font and black background. See the examples, for a basic theme as a CSS definition. At the same, it also properly escapes HTML unsafe characters (&,<,>,etc.) into their proper HTML representation.
To build, a simple Makefile handles it all.
To run the tests for ansi_up, run
npm install to install dev dependencies. Then:
$ make test
This code was developed by Dru Nelson (https://github.com/drudru).
Thanks goes to the following contributors for their patches:
(The MIT License)
Copyright (c) 2011 Dru Nelson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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