What is the official name of the JavaScript language standard?

The official name of the JavaScript language standard is ECMAScript.

JavaScript is the widely used language implementation and branding, while ECMAScript is the standardized specification that defines its core syntax and behavior. The standard is developed through Ecma International, with the language specification published as ECMA-262. Web browsers, server runtimes, and other engines use this specification as a shared compatibility target.

The name arose from trademark and standardization concerns surrounding JavaScript. After JavaScript became popular in the mid-1990s, the language was submitted to Ecma for formal standardization. The first edition of the ECMAScript standard appeared in 1997. Modern JavaScript engines implement successive ECMAScript editions, although support for individual features can vary by runtime or version.

Names such as ES5, ES6, and ES2015 refer to particular editions or yearly naming conventions, not alternative official names for the entire standard. ES6 is also commonly called ECMAScript 2015, because the sixth edition was released in 2015.