The development of ECMAScript 6 took about four years, and after that, TC-39 decided that such a long development process was unsustainable. Instead, it moved to a yearly release cycle to ensure new language features would make it into development sooner.

More frequent releases mean that each new edition of ECMAScript should have fewer new features than ECMAScript 6. To signify this change, new versions of the specification no longer prominently feature the edition number and instead refer to the year in which the specification was published. As a result, ECMAScript 6 is also known as ECMAScript 2015, and ECMAScript ...

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