Utilities for escaping and interpolating HTML strings in JS

HtmlUtils.js

// Requires underscore.js
var HTML,
    Html;

HTML = function HTML (string) {
    this.string = string;
};
HTML.prototype.toString = function toString() {
    return this.string.toString();
}

Html = function Html(string, options) {
    if (!_.isString(string) && !(string instanceof HTML)) {
        throw new Error('Expected a string');
    }
    if (!_.isObject(options) && typeof options !== 'undefined') {
        throw new Error('If provided, options must be an object');
    }

    if (_.isUndefined(options)) {
        return new HTML(string);
    } else {
        return new HTML(string.replace(/{\w+}/g, function (parameter) {
            var substitution = options[parameter.slice(1,-1)];
            if (substitution instanceof HTML) {
                return substitution;
            } else {
                return _.escape(substitution);
            }
        }));
    }
};