docs

packages/eslint-plugin/docs/rules/wp-globals-usage.md

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+# WordPress globals usage (wp-globals-usage)
+
+To enable the use of feature flags in Gutenberg some globals are used, such as `IS_GUTENBERG_PLUGIN` and `SCRIPT_DEBUG`.
+
+There are a few rules around using this constant:
+
+-   Only access the globals via `globalThis`, e.g. `globalThis.IS_GUTENBERG_PLUGIN`. This allows the variables to be replaced compile time.
+-   The globals should only be used as a conditional test (negation is allowed).
+
+## Rule details
+
+Examples of **incorrect** code for this rule:
+
+```js
+if ( IS_GUTENBERG_PLUGIN ) {
+	// implement feature here.
+}
+```
+
+```js
+if ( window[ 'IS_GUTENBERG_PLUGIN' ] ) {
+	// implement feature here.
+}
+```
+
+```js
+if ( globalThis.IS_GUTENBERG_PLUGIN == 1 ) {
+	// implement feature here.
+}
+```
+
+```js
+if ( globalThis.IS_GUTENBERG_PLUGIN === true ) {
+	// implement feature here.
+}
+```
+
+```js
+if ( true || globalThis.IS_GUTENBERG_PLUGIN ) {
+	// implement feature here.
+}
+```
+
+```js
+const isMyFeatureActive = globalThis.IS_GUTENBERG_PLUGIN;
+```
+
+Examples of **correct** code for this rule:
+
+```js
+if ( globalThis.IS_GUTENBERG_PLUGIN ) {
+	// implement feature here.
+}
+```
+
+```js
+if ( ! globalThis.IS_GUTENBERG_PLUGIN ) {
+	return;
+}
+```