immutability - Correct way to permanently alter a JavaScript string -

in ruby, if want modify string , have change original string, can use ! bang character.

string = "hello" string.capitalize! > "hello" string > "hello"  

in javascript, can't find equivalence. modifying string uppercase instance returns original string after first instance.

var string = "hello"; string.touppercase(); > "hello" string > "hello" 

i know can save variable such

var uppercasestring = string.touppercase(); 

but seems inefficient , undesirable purposes.

i know must obvious, missing?

the return value of touppercase new string capitalized. if want keep , throw away original, use this:

string = string.touppercase(); 

btw, when entering js statements on command line of node.js , similar environments, prints result of evaluating each expression, why see uppercase version if type

string.touppercase(); 

as have deduced has no effect on original string.