Asynchronous Template Loader

gistfile1.js

TemplateLoader = (function(){
    var template_cache = {};
    var template_path = '/tmpl';
    var loading_cache = {};
    
    var load_template = function(template, callback){
        var deferred = $.Deferred();
        if(_.isUndefined(template) || !_.isFunction(callback)){
            return false;
        }

        template = template.replace("#","");
        
        if(_.has(template_cache, template)){
            console.log('Template '+template+' is already cached locally');
            callback(template_cache[template]);
        } else if(loading_cache.template){
            console.log('Template '+template+' is being loaded, so adding a callback to the deferred queue');
            deferred.done(callback);
        } else {
            console.log('Template '+template+' is not loading nor in cache, retreive from server');
            loading_cache[template] = true;
            deferred.done(callback);
            $.ajax({
                type: "GET",
                url: join_paths(template_path, template),
                success: function(resp){
                    console.log('Template '+template+' has finished loading from the server');
                    template_cache[template] = resp;
                    loading_cache[template] = false
                    deferred.resolve(resp);
                }
            });
        }
    };
    
    var join_paths = function(){
        // strip off all / from start and end
        return "/"+_.map(arguments, function(arg){
            if(_.isString(arg)){
                if(arg.slice(0, 1) === '/'){
                   arg = arg.slice(1);
                }
                if(arg.slice(-1) === '/'){
                    arg = arg.slice(0, -1);
                }                
            }
            return arg;
        }).join('/');
    };
    
    return {load_template: load_template};
}());