htmlout

This library lets you use (a very restricted subset of) HTML to style console output.

Example

Say you have this string in a variable called html:

<p><span style="color: #0f0">Hello!</span> <strong>This text should be bold.</strong></p>
<p>And then <strike>here we have struck-out text</strike>, <u>underlined text</u>, etc.</p>

Now we pass that to htmlout:

htmlout(html);

Output:

You can even apply stylesheets. For instance, suppose you have the following CSS in a variable called css:

.info {
  color: blue;
}
 
.success {
  color: lime;
  text-decoration: underline;
}
 
.warning {
  color: orange;
  font-weight: bold;
}
 
.fail {
  color: red;
  background-color: yellow;
  font-weight: bold;
}

And then this is html:

<p class="info">Here is some information.</p>
<p class="success">The mission was a success!</p>
<p class="warning">You are running low on fuel.</p>
<p class="fail">System failure!</p>

Then you use htmlout.withCSS:

htmlout.withCSS(css)(html);

Output:

This project is used by console-highlight to do syntax highlighting in the console. Here's an example:

Supported CSS Styles

Obviously (well, at least without herculean effort), it isn't possible to support all CSS styles from a console. These are the styles that are at least partially supported:

• color
• background-color
• font-style (normal or italic on some terminals)
• font-weight (normal or bold)
• text-decoration (none, underline, strikethrough on some terminals)
• text-transform (none, uppercase, lowercase, or capitalize)

How it works

htmlout follows a relatively simple process:

1. First, the HTML is parsed using jsdom, which provides a DOM and handles stylesheets.
2. htmlout then iterates over every text node of the DOM, translating the relevant CSS style rules to terminal escape sequences. For example the CSS rule font-weight: bold; is translated to the escape sequence '\x1B[1m' and '\x1B[21m'.
3. The console does not support just any arbitrary color. htmlout uses nearest-color to make a best effort to translate any color in CSS to a valid escape sequence. This actually yields very good results, especially on terminals that support 256 colors. (This isn't 100% implemented yet. Colors in hex or RGB format should work; but for short names like 'aqua', only the 16 basic colors are supported right now. HSL format isn't supported at all.)

That's about it! If you have questions or run into issues, let me know!