Convert terminal output including ANSI escape sequences to HTML. Only handles simple cases!

term2html.js

'use strict';

var defaultColors = [ '#000', '#D00', '#00CF12', '#C2CB00', '#3100CA',
	'#E100C6', '#00CBCB', '#C7C7C7', '#686868', '#FF5959', '#00FF6B',
	'#FAFF5C', '#775AFF', '#FF47FE', '#0FF', '#FFF' ];

function term2html(text, options) {
	options = options || {};
	var colors = options.colors || defaultColors;

	// EL – Erase in Line: CSI n K.
	// Erases part of the line. If n is zero (or missing), clear from cursor to
	// the end of the line. If n is one, clear from cursor to beginning of the
	// line. If n is two, clear entire line. Cursor position does not change.
	text = text.replace(/^.*\u001B\[[12]K/mg, '');

	// CHA – Cursor Horizontal Absolute: CSI n G.
	// Moves the cursor to column n.
	text = text.replace(/^(.*)\u001B\[(\d+)G/mg, function(_, text, n) {
		return text.slice(0, n);
	});

	// SGR – Select Graphic Rendition: CSI n m.
	// Sets SGR parameters, including text color. After CSI can be zero or more
	// parameters separated with ;. With no parameters, CSI m is treated as
	// CSI 0 m (reset / normal), which is typical of most of the ANSI escape
	// sequences.
	var state = {
		bg: -1,
		fg: -1,
		bold: false,
		underline: false,
		negative: false
	};
	text = text.replace(/\u001B\[([\d;]+)m([^\u001B]+)/g, function(_, n, text) {
		// Update state according to SGR codes.
		n.split(';').forEach(function(code) {
			code = code | 0;
			if (code === 0) {
				state.bg = -1;
				state.fg = -1;
				state.bold = false;
				state.underline = false;
				state.negative = false;
			} else if (code === 1) {
				state.bold = true;
			} else if (code === 4) {
				state.underline = true;
			} else if (code === 7) {
				state.negative = true;
			} else if (code === 21) {
				state.bold = false;
			} else if (code === 24) {
				state.underline = false;
			} else if (code === 27) {
				state.negative = false;
			} else if (code >= 30 && code <= 37) {
				state.fg = code - 30;
			} else if (code === 39) {
				state.fg = -1;
			} else if (code >= 40 && code <= 47) {
				state.bg = code - 40;
			} else if (code === 49) {
				state.bg = -1;
			} else if (code >= 90 && code <= 97) {
				state.fg = code - 90 + 8;
			} else if (code >= 100 && code <= 107) {
				state.bg = code - 100 + 8;
			}
		});

		// Convert color codes to CSS colors.
		var bold = state.bold * 8;
		var fg, bg;
		if (state.negative) {
			fg = state.bg | bold;
			bg = state.fg;
		} else {
			fg = state.fg | bold;
			bg = state.bg;
		}
		fg = colors[fg] || '';
		bg = colors[bg] || '';

		// Create style element.
		var style = '';
		if (bg) {
			style += 'background-color:' + bg + ';';
		}
		if (fg) {
			style += 'color:' + fg + ';';
		}
		if (bold) {
			style += 'font-weight:bold;';
		}
		if (state.underline) {
			style += 'text-decoration:underline';
		}
		var html = text.
			replace(/&/g, '&amp;').
			replace(/</g, '&lt;').
			replace(/>/g, '&gt;');

		// Return HTML for this section of formatted text.
		if (style) {
			return '<span style="' + style + '">' + html + '</span>';
		} else {
			return html;
		}
	});

	return text.replace(/\u001B\[.*?[A-Za-z]/g, '');
}

module.exports = term2html;

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