Does JavaScript Use String Interning?

String Interning in JavaScript

This question explores whether JavaScript implementations like V8 and WebKit's JavaScriptCore utilize string interning for JavaScript strings. String interning is a technique where identical strings in a program are stored in a single location in memory, effectively creating a canonical representation.

Answer:

Yes, common JavaScript engines indeed employ string interning for literal strings, identifiers, and other constant strings within JavaScript source code. However, it's worth noting that implementation specifics may vary across engines.

Implementation Details:

Interning typically occurs during parsing or compilation. The engine creates a hash table that maps strings to their interned representations. When a new string is encountered, it is hashed and compared to the interned strings. If a matching string exists, the engine will use the interned representation instead of creating a new instance.

String Objects vs. String Values:

It's crucial to differentiate between string values and String objects. String values are interned, but String objects are not. Interning String objects would result in incorrect behavior since String objects provide additional functionality beyond simple string representation.

The above is the detailed content of Does JavaScript Use String Interning?. For more information, please follow other related articles on the PHP Chinese website!