From 024fbaf09e904882e3729faf306e97fe335290dd Mon Sep 17 00:00:00 2001 From: atomiks Date: Mon, 19 Mar 2018 12:50:55 +1000 Subject: [PATCH] Create isBrowser.md --- snippets/isBrowser.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 snippets/isBrowser.md diff --git a/snippets/isBrowser.md b/snippets/isBrowser.md new file mode 100644 index 000000000..2145a2331 --- /dev/null +++ b/snippets/isBrowser.md @@ -0,0 +1,19 @@ +### 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. + +```js +const isBrowser = () => ![typeof window, typeof document].includes('undefined') +``` + +```js +isBrowser() // true (browser) +isBrowser() // false (Node) +```