Question

How can this object be rewritten so you don’t need to declare it with “new”?

var Lang = new function(){
    this.get = function(str, trans){
        if(TRANSLATE[str]){
            var str = TRANSLATE[str][LANG];
            if(count_obj(trans) > 0){
                for(var key in trans){
                    str = str.replace('%'+key+'%', trans[key]);
                }
            }
        }

        return str;
    };
};

To something like this:

var Lang = {
get : function(){}
};

Answer 1

You wrote the solution to your own question in the question…this is a perfectly valid way to create an object in javascript:

var Lang = {
    get: function(str, trans){
        if(TRANSLATE[str]){
            var str = TRANSLATE[str][LANG];
            if(count_obj(trans) > 0){
                for(var key in trans){
                    str = str.replace('%'+key+'%', trans[key]);
                }
            }
        }

        return str;
    };
};

If you want private variables, the usual way to do that is to create a function with local variables that return the object with those variables encapsulated in a closure like so:

var Lang = (function() {
    var p1; // private variable
    var p2; // another private variable

    return {
       getP1: function () {
          return p1;
       },
       setP1: function(value) {
          p1 = value;
       }
    };
})();

Note that the function that creates the object you want is executed right away and returns the object with two private variables captured in the closure. Those variables will not be accessible from outside the object.