Implements simple character-count-based word wrapping with regular expressions in JavaScript

regex-wordwrap.js

/**
 * Wraps the specified string onto multiple lines by character count.
 *
 * Words (consecutive non-space characters) are not split up.
 * Lines may be shorter than `len` characters as a result.
 * Careful: words longer than `len` will be dropped!
 *
 * @param str The string to wrap.
 * @param len The max character count per line.
 *
 * @returns A newline-delimited string.
 */
function wordwrap(str, len) {
	return (
            str.match(
                new RegExp('(\\S.{0,' + (len-1) + '})(?=\\s+|$)', 'g')
            ) || []
        ).join('\n');
}

// Example usage:
wordwrap('The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.', 25)
// Produces this string:
// The quick brown fox jumps
// over the lazy dog. The
// quick brown fox jumps
// over the lazy dog.