Babel

https://packagecontrol.io/packages/Babel

Setting as the default syntax

To set it as the default syntax for a particular extension: 1. Open a file with that extension, 2. SelectViewfrom the menu, 3. ThenSyntax->Open all with current extension as...->Babel->JavaScript (Babel). 4. Repeat this for each extension (e.g.:.jsand.jsx).