js-switch-vs-regex

var timethis = function (f, n) {
    var start = new Date();
    for (var i=n; i > 0; --i) f();
    var end = new Date();
    var delta = end.getTime() - start.getTime();
    print(n + ' iterations took ' + delta + 'ms');
};

var switchcase = function (tag) {

    var selfClosing = false;

    switch(tag.toLowerCase()) {
        case "area":
        case "base":
        case "basefont":
        case "br":
        case "hr":
        case "input":
        case "img":
        case "link":
        case "meta":
        selfClosing = true;
        break;
    }

    return selfClosing;
};

var regex_one = function (tag) {
    return tag.match(/^(area|base|basefont|br|hr|input|img|link|meta)$/i) ? true: false;
};

var re = new RegExp('^(area|base|basefont|br|hr|input|img|link|meta)$', 'i');
var regex_two = function (tag) {
    return re.test(tag);
};

var taghash = {
    area: true, base: true, basefont: true, br: true, hr: true, input: true,
    img: true, link: true, meta: true
};
var hash = function (tag) {
    return taghash[tag.toLowerCase()] ? true : false;
};

var tags = [];

(function () {
    var i = 1000;
    var possible_tags = [
        'area', 'base', 'basefont', 'br', 'hr', 'input', 'img', 'link', 'meta',
        'a', 'b', 'blockquote', 'body', 'div', 'font', 'head', 'li', 'ol', 'q',
        'script', 'span', 'table', 'tbody', 'td', 'thead', 'title', 'tr', 'ul'
    ];

    var l = possible_tags.length;
    while (i--) {
        tags.push( possible_tags[ Math.floor(Math.random() * l) ] );
    }
})();

print('switch/case:');
timethis(function () {
    var i = tags.length;
    while (i-- > 0) {
        switchcase(tags[i]);
    }
}, 1000);

print('regex version 1 (compile on each hit):');
timethis(function () {
    var i = tags.length;
    while (i-- > 0) {
        regex_one(tags[i]);
    }
}, 1000);

print('regex version 2 (compile once):');
timethis(function () {
    var i = tags.length;
    while (i-- > 0) {
        regex_two(tags[i]);
    }
}, 1000);

print('hash key check:');
timethis(function () {
    var i = tags.length;
    while (i-- > 0) {
        hash(tags[i]);
    }
}, 1000);