ES6ES2015

ES6, commonly called ES2015, is the sixth edition of the ECMAScript standard, published by ECMA International in 2015. It represents a major revision of JavaScript, introducing a broad set of syntax improvements and new built-in features designed to improve developer productivity, readability, and modularity. ES2015 remains a landmark in the language’s evolution, providing a foundation for many subsequent enhancements described in later editions.

Key language features include block-scoped variables with let and const; arrow functions; template literals; object and array destructuring; default parameters; and rest and spread operators. It also adds a class syntax, modules via import and export, extended object literals, the for...of loop, and generators with function* and yield. The new Promise API enables asynchronous programming, and the Symbol primitive provides unique object keys. In addition, Map, Set, WeakMap, and WeakSet offer new collection types.

Impact and adoption: The changes demanded toolchain updates (transpilers such as Babel) and polyfills for older environments. After 2015–2016, major browsers and Node.js added increasing native support, accelerating widespread adoption. ES2015's modular and functional features influenced coding style and library design, and many features remain in daily use in modern JavaScript development.

Relation to later editions: ES2016 onward introduced smaller incremental improvements, but ES2015 continues to serve as the core baseline for modern JavaScript syntax and capabilities. The npm ecosystem, module systems, and modern frameworks reflect its enduring influence.