Sluggify a string replacing spaces by "-", lowercasing and replacing accents and removing special chars

sluggify.js

/**
 * Sluggify a string replacing spaces by "-", lowercasing and replacing accents and removing special chars.
 *
 * @type {Function}
 * @return {String}
 */
String.prototype.slug = String.prototype.slug || function() {
    var replace = this.replace(/\s/g, '-');
    replace = replace.toLowerCase();

    // Replace accents and special chars
    var base_chars = [
        '1', '2', '3', '4', '5', '6', '7', '8', '9',
        '0', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
        'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
        'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
        '-', '_', ' '
    ];

    replace = replace.normalize('NFKD').split('').map(function(c) {
        return base_chars.find(function(bc) {
            return bc.localeCompare(c, 'en', {
                sensitivity: 'base'
            }) == 0;
        });
    }).join('');

    return replace;
};

test.js

console.log('It\'s co0l : ÀÁÂÃÄÅàáâãäåÒÓÔÕÕÖØòóôõöøÈÉÊËèéêëðÇçÐÌÍÎÏìíîïÙÚÛÜùúûüÑñŠšŸÿýŽž Then : @()[]<>§:!/.?\\=+°0123456789²^¨$£¤%*µ'.slug());
// Returns : "its-co0l--aaaaaaaaaaaaoooooooooooooeeeeeeeedccdiiiiiiiiuuuuuuuunnssyyyzz-then--01234567892 "