Do JavaScript Engines Utilize String Interning?

Introduction:
In programming, string interning refers to the process of reusing existing string objects instead of creating new ones for identical strings. This optimization technique aims to reduce memory usage and improve performance. The question arises whether common JavaScript engines, including V8 and WebKit's JavaScriptCore, implement string interning for JavaScript strings.

Question:
Do common JavaScript engines, namely V8 and WebKit's JavaScriptCore, employ string interning for JavaScript strings or maintain multiple copies of identical strings in memory?

Answer:
Yes, generally, common JavaScript engines like V8 and JavaScriptCore implement string interning for JavaScript strings. The specific implementation details, such as the scope of interning and the time of its occurrence, may vary across different engines.

It's important to note that string interning applies to literal strings, identifiers, and other constant strings found in JS source code. However, it does not extend to String Objects. String Objects themselves are not interned, as such behavior would be inappropriate.