is-gutenberg-plugin.md

The IS_GUTENBERG_PLUGIN global (is-gutenberg-plugin)

To enable the use of feature flags in Gutenberg, the IS_GUTENBERG_PLUGIN global constant was introduced. This constant is replaced with a boolean value at build time using webpack's define plugin.

There are a few rules around using this constant:

• Only access IS_GUTENBERG_PLUGIN via process.env, e.g. process.env.IS_GUTENBERG_PLUGIN. This is required since webpack's define plugin only replaces exact matches of process.env.IS_GUTENBERG_PLUGIN in the codebase.
• The IS_GUTENBERG_PLUGIN variable should only be used as a simple boolean expression.
• IS_GUTENBERG_PLUGIN should only be used within the condition of an if statement, e.g. if ( process.env.IS_GUTENBERG_PLUGIN ) { // implement feature here } or ternary process.env.IS_GUTENBERG_PLUGIN ? something : somethingElse. This rule ensures code that is disabled through a feature flag is removed by dead code elimination.

Rule details

Examples of incorrect code for this rule:

if ( IS_GUTENBERG_PLUGIN ) {
	// implement feature here.
}

if ( window[ 'IS_GUTENBERG_PLUGIN' ] ) {
	// implement feature here.
}

if ( process.env.IS_GUTENBERG_PLUGIN == 1 ) {
	// implement feature here.
}

if ( process.env.IS_GUTENBERG_PLUGIN === true ) {
	// implement feature here.
}

if ( true || process.env.IS_GUTENBERG_PLUGIN ) {
	// implement feature here.
}

const isMyFeatureActive = process.env.IS_GUTENBERG_PLUGIN;

Examples of correct code for this rule:

if ( process.env.IS_GUTENBERG_PLUGIN ) {
	// implement feature here.
}

if ( ! process.env.IS_GUTENBERG_PLUGIN ) {
	return;
}