Editing ECMAScript (section)

=== Transpiling ===
{{Main|JavaScript#transpilers}}
Since ES 2015, transpiling JavaScript has become very common. Transpilation is a [[source-to-source compilation]] in which newer versions of JavaScript are used, and a transpiler rewrites the source code so that it is supported by older browsers. Usually, transpilers transpile down to ES3 to maintain compatibility with all versions of browsers. The settings to transpile to a specific version can be configured according to need. Transpiling adds an extra step to the build process and is sometimes done to avoid needing [[Polyfill (programming)|polyfills]]. Polyfills create new features for older environments that lack them.<!-- The polyfill article is much better --> Polyfills do this at runtime in the interpreter, such as the user's browser or on the server. Instead, transpiling rewrites the ECMA code itself during the build phase of development before it reaches the interpreter.