Does javascript have a method to replace part of a string without creating a new string?

var str = "This is a string";
var thing = str.replace("string","thing");

console.log( str )
>> "This is a string" 

console.log( thing )
>> "This is a thing" 

Is there another method I can use, besides replace, that will alter the string in place without giving me a new string object?

No, strings in JavaScript are immutable.

Not that i am aware of, however if the reason you want to do this is just to keep your code clean you can just assign the new string the the old variable:

var string = "This is a string";
string = string.replace("string", "thing");

Of course this will just make the code look a bit cleaner and still create a new string.