JS字符串/数字和垃圾收集

Question

tl;dr

Does the following line of code create an object (like a JavaScript String object or a JavaScript Number object) to combine the string primitive and the number?

var scouterSays = "powerlvl" + 9001;

Full Question

I'm writing a game engine in JavaScript and am trying to be very careful with garbage collection. I've read through http://www.scirra.com/blog/76/how-to-write-low-garbage-real-time-javascript and http://buildnewgames.com/garbage-collector-friendly-code/ which have been very helpful. I've implemented object pooling and have avoided array manipulation in favor of linked lists whenever possible.

Now if I understand it correctly, if I call a string method on a primitive string, a string object will be created and replaces my primitive string. Examples are length, substring, indexOf, and so on. Since I use strings to identify object types with object pooling, I am concerned that I am creating garbage each time I pull an object from the pool.

In short, will the following cause an object (like a JavaScript String object or a JavaScript Number object) to be created?

var byteSize = 4;
var objectType = "msg" + byteSize; //does this create a JS String/Number object?
var message = gameengine.pool.acquire(objectType);

Also, a related question, will use of bitwise operations (like ~~() or << or >>) cause a JavaScript object to be created as well?

Answer 1

I have zero trust to JavaScript GC and this is my base reason to stay away from this language. Anyway, my attempt to reply is:

var x = 1;
alert(typeof x); //number

var n = new Number(1);
alert(typeof n); //object

var scouterSays = "powerlvl" + 9001;
alert(typeof scouterSays); //string

var txt = new String("string");
alert(typeof txt); //object

var test1 = new Boolean(true);
var test2 = String(test1); //convert object to string
alert(typeof test2); //string