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30-seconds-of-code/snippets/isBrowser.md
2018-03-19 12:50:55 +10:00

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isBrowser

Determines if the current runtime environment is a browser so that front-end modules can run on the server (Node) without throwing errors.

Use Array.includes() on the typeof values of both window and document (globals usually only available in a browser environment unless they were explicitly defined), which will return true if one of them is undefined. typeof allows globals to be checked for existence without throwing a ReferenceError.

If both of them are not undefined, then the current environment is assumed to be a browser.

const isBrowser = () => ![typeof window, typeof document].includes('undefined')
isBrowser() // true (browser)
isBrowser() // false (Node)