ES2025 adds native Set methods for union, intersection, and difference in JavaScript

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JavaScript's ES2025 specification has introduced seven new built-in methods for the Set object, including union(), intersection(), difference(), symmetricDifference(), isSubsetOf(), isSupersetOf(), and isDisjointFrom(). Although the Set data structure has been part of JavaScript since ES6 in 2015, it lacked native support for standard set-theory operations until now. Each method accepts any set-like object — defined as having a size property, a has() method, and a keys() iterator — meaning Maps and custom structures are also compatible. Previously, developers had to write multi-line manual workarounds using spread operators and filter functions to achieve the same results. TypeScript added type support for these methods in version 5.5 under the ES2025 library configuration.

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