What JavaScript syntax is new? What is safe to use for any browser? How do we find this out?

These questions all have to do with browser compatibility, the idea that the browsers have to update to use the latest JavaScript features, some browsers haven’t done so yet, and some users haven’t updated their browser to the latest version. When we design a site for browser compatibility, we design our site to work correctly for as many different browsers and browser versions as possible. When thinking about browser compatibility, it is helpful to have a resource that will tell us which language features are supported by which browser versions.

Tools such as caniuse.com provide helpful browser compatibility information. On that site, you can search for language features and see:

  • The browser versions that support those features
  • Which browser versions don’t support those features
  • What percentage of internet users are using these versions

From this information, you can see whether your site can reach the number of users you want. In the upcoming exercises, we will learn how Babel can improve our site’s compatibility across browsers and their versions.


On the right, we have caniuse.com‘s display of browser support for ES6 syntax. Explore these results, or look up specific ES6+ JavaScript syntax using their search feature.

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