Does JavaScript Utilize String Interning?

String Interning in JavaScript Implementations

While working with JavaScript, it's essential to optimize performance and memory usage. String interning is a technique commonly employed by programming languages to save memory. Does this mechanism extend to JavaScript engines like V8 and WebKit's JavaScriptCore?

Do JavaScript Engines Utilize String Interning?

Yes, common JavaScript engines do employ string interning. When you create a literal string, an identifier, or any other constant string in JavaScript code, it is generally interned. This means that multiple instances of identical strings are not kept in memory; instead, the JavaScript engine stores a single representation and assigns references to that single instance.

Implementation Details

The specific implementation details of string interning may vary between different JavaScript engines. For example, V8 interns any string used as a property key or accessed via a dot operator, while SpiderMonkey interns all literal strings.

String Value versus String Object

It's important to note that string interning applies to primitive string values. JavaScript also provides String objects, which are not interned. Interning String objects would introduce incorrect behavior as they are mutable.

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