gatsby-browser.js

/**
 * Implement Gatsby's Browser APIs in this file.
 *
 * See: https://www.gatsbyjs.org/docs/browser-apis/
 */

// onPreRouteUpdate() and onRouteUpdate() are called before onInitialClientRender,
// use initialized flag to ensure that window.onGatsbyPreRouteUpdate() and
// window.onGatsbyRouteUpdate() will not be called before
// window.onGatsbyInitialClientRender() has run
let initialized = false

exports.onInitialClientRender = () => {
	initialized = true
	if (
		'onGatsbyInitialClientRender' in window &&
		typeof window.onGatsbyInitialClientRender === 'function'
	) {
		window.onGatsbyInitialClientRender()
	}
	if (
		'onGatsbyRouteUpdate' in window &&
		typeof window.onGatsbyRouteUpdate === 'function'
	) {
		window.onGatsbyRouteUpdate()
	}
}

exports.onRouteUpdate = () => {
	if (
		initialized &&
		'onGatsbyRouteUpdate' in window &&
		typeof window.onGatsbyRouteUpdate === 'function'
	) {
		window.onGatsbyRouteUpdate()
	}
}

exports.onPreRouteUpdate = () => {
	if (
		initialized &&
		'onGatsbyPreRouteUpdate' in window &&
		typeof window.onGatsbyPreRouteUpdate === 'function'
	) {
		window.onGatsbyPreRouteUpdate()
	}
}