JavaScript programming language: Final chance to drop early Web Components API before Chrome ditches support

Google will continue to support v0 of the API in Chrome until around February 2020 to give developers more time to upgrade.

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Web developers who are still using Google's early version of the Web Components API on their sites have been granted a stay of execution.

The Web Components API allows developers to use JavaScript to define custom reusable HTML tags for use on their site and today is supported by every major browser.

However, Web Components started out as a Google initiative and in its first iteration, known as v0, the JavaScript API was only supported in Chrome.

In a bid to encourage developers to move to the cross-browser Web Components v1 API, Google had been planning to remove support for the v0 API with the release of Chrome 73, in May.

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But Google held off stripping out support for the API to give developers more time to upgrade, and now says it will continue supporting the v0 API until the release of Chrome 80, in around February 2020.

"Because enough developers requested more time to migrate, the APIs have not yet been removed from Chrome," writes Google's web developer team.

Google has released a series of guides for web developers who want to check if their site would be affected by the removal of support for the v0 API, including instructions for how to disable support for the v0 API to see how the site functions. 

For those who are unable to upgrade at present, Google also provides additional polyfill JavaScript code that allows Web Components v0 to work in browsers that don't support it.

If developers aren't certain whether they're using an obsolete version of the Web Components API, then can open the DevTools Console by hitting Ctrl+Shift+J (Cmd+Shift+J on Mac) in Chrome and checking for messages starting with "[Deprecation]", which will detail the APIs whose support is due to be removed.

"The Web Components v0 draft APIs are going away. If you take one thing away from this post, make sure you test your app with the v0 APIs disabled and load the polyfills as needed," the Google team write.

Those developers using version 1 or 2 of Polymer, Google's JavaScript library for building web apps, will indirectly be using v0 of Web Components, although they're unlikely to be affected by the removal of support, due to Polymer bundling polyfill code to handle cases where the v0 API isn't supported.

Web Components are an increasingly popular way for web developers to reuse code for features like custom UIs in web pages and apps, with millions of sites using version 1 of the Web Components API.

To find out more about the popular JavaScript spin-off language TypeScript, read TechRepublic's round-up of the best free resources for learning the language online.

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