client/lib/analytics/ad-tracking.js
function recordOrderInFacebook( cart, orderId, wpcomJetpackCartInfo ) {
	if ( ! isAdTrackingAllowed() || ! isFacebookEnabled ) {
		return;
	}

	/**
	 * We have made a conscious decision to ignore the 0 cost carts, such that these carts are not considered
	 * a conversion. We will analyze the results and make a final decision on this.
	 */
	if ( cart.total_cost < 0.01 ) {
		debug( 'recordOrderInFacebook: skipping due to a 0-value cart.' );
		return;
	}

	const currentUser = user.get();
	const userId = currentUser ? hashPii( currentUser.ID ) : 0;

	// WPCom

	if ( wpcomJetpackCartInfo.containsWpcomProducts ) {
		const params = [
			'trackSingle',
			TRACKING_IDS.facebookInit,
			'Purchase',
			{
				product_slug: wpcomJetpackCartInfo.wpcomProducts
					.map( product => product.product_slug )
					.join( ', ' ),
				value: wpcomJetpackCartInfo.wpcomCost,
				currency: cart.currency,
				user_id: userId,
				order_id: orderId,
			},
		];
		debug( 'recordOrderInFacebook: WPCom', params );
		window.fbq( ...params );
	}

	// Jetpack

	if ( wpcomJetpackCartInfo.containsJetpackProducts ) {
		const params = [
			'trackSingle',
			TRACKING_IDS.facebookJetpackInit,
			'Purchase',
			{
				product_slug: wpcomJetpackCartInfo.jetpackProducts
					.map( product => product.product_slug )
					.join( ', ' ),
				value: wpcomJetpackCartInfo.jetpackCost,
				currency: cart.currency,
				user_id: userId,
				order_id: orderId,
			},
		];
		debug( 'recordOrderInFacebook: Jetpack', params );
		window.fbq( ...params );
	}
}
function recordOrderInFacebook( cart, orderId, wpcomJetpackCartInfo ) {
	if ( ! isAdTrackingAllowed() || ! isFacebookEnabled ) {
		return;
	}

	/**
	 * We have made a conscious decision to ignore the 0 cost carts, such that these carts are not considered
	 * a conversion. We will analyze the results and make a final decision on this.
	 */
	if ( cart.total_cost < 0.01 ) {
		debug( 'recordOrderInFacebook: skipping due to a 0-value cart.' );
		return;
	}

	const currentUser = user.get();
	const userId = currentUser ? hashPii( currentUser.ID ) : 0;

	// WPCom

	if ( wpcomJetpackCartInfo.containsWpcomProducts ) {
		const params = [
			'trackSingle',
			TRACKING_IDS.facebookInit,
			'Purchase',
			{
				product_slug: wpcomJetpackCartInfo.wpcomProducts
					.map( product => product.product_slug )
					.join( ', ' ),
				value: wpcomJetpackCartInfo.wpcomCost,
				currency: cart.currency,
				user_id: userId,
				order_id: orderId,
			},
		];
		debug( 'recordOrderInFacebook: WPCom', params );
		window.fbq( ...params );
	}

	// Jetpack

	if ( wpcomJetpackCartInfo.containsJetpackProducts ) {
		const params = [
			'trackSingle',
			TRACKING_IDS.facebookJetpackInit,
			'Purchase',
			{
				product_slug: wpcomJetpackCartInfo.jetpackProducts
					.map( product => product.product_slug )
					.join( ', ' ),
				value: wpcomJetpackCartInfo.jetpackCost,
				currency: cart.currency,
				user_id: userId,
				order_id: orderId,
			},
		];
		debug( 'recordOrderInFacebook: Jetpack', params );
		window.fbq( ...params );
	}
}
Records an order in Facebook (a single event for the entire order)

@param {Object} cart - cart as `CartValue` object
@param {Number} orderId - the order id
@param {Object} wpcomJetpackCartInfo - info about WPCOM and Jetpack in the cart
@returns {void}