@axway/api-builder-uri-utils/src/escapeExpressRegex.js

A collection of URI utility functions for API Builder

/**
 * Express.js supports regex routing.  For example, '/ab+cd' would match "abcd",
 * "abxcd", etc. (see http://expressjs.com/en/guide/routing.html#route-paths).
 * This method will escape regex characters in `path` so that they are not
 * accidentally interpreted as regex.  In addition, this needs to avoid escaping
 * the `?` because it is an optional parameter in express (when the fragment
 * starts with `:`).
 *
 * As an example, consider "A(B)".  This URI component does not require
 * escaping.  `encodeURI` returns "A(B)".  However, as an express URI, this
 * would be interpreted as a regular expression.  To avoid that, this will
 * escape the path "A[(]B[)]".
 *
 * @param {string} path - The path to escape.
 * @return {string} The escaped path.
 */
function escapeExpressRegex(path) {
	// https://expressjs.com/en/guide/routing.html
	return path.replace(/([()*+])/g, '[$1]') // express regex escape
		// The following code is questionable. It describes a literal ? in an
		// express path. You can NEVER hit a path with a literal question mark
		// since this represents the query portion of the string which will be
		// stripped before the path matching takes place. You cannot provide an
		// encoded question mark either since this will not match a literal one.

		// https://tools.ietf.org/html/rfc3986#page-22
		// fought with regex for a while and gave up - this took 2m to write ;)
		// it is going to split the path, then find any part that is not an
		// express parameter and then escape the ?.
		.split('/').map((part) => {
			if (!part.startsWith(':')
				&& part.includes('?')) {
				return part.replace(/\?/g, '[?]');
			} else if (part.startsWith(':')
				&& part.includes('?')
				&& !part.endsWith('?')) {
				return part.replace(/\?/g, '[?]');
			}
			return part;
		}).join('/');
}

module.exports = escapeExpressRegex;