Sample code from LaunchDarkly "Black Friday" blog post

flagged-feature.java

public List<Comment> getProductComments(Product product) {
	// The app contains its own singleton service to hold one instance
// of the LaunchDarkly client.
	ldClient = LaunchDarklyService.getClient();
	ldUser = LaunchDarklyService.getUserFromContext(context);
	boolean showFeature = ldClient.boolVariation("show-comments", user, false);
	// If the feature is turned off, just return an empty list of comments
	If (!showFeature) {
		return Collections.emptyList();
	}

	// The rest of this method, containing heavy SQL queries, goes here...
}

node-limiter.p1.js

const LIMIT_FLAG_KEY = "throttle_api_reqs";
const limit_on = ldClient.variation(LIMIT_FLAG_KEY, {}, false);
const limiter = new Bottleneck({ maxConcurrent: limit_on ? 1000 : 10000 });

node-limiter.p2.js

// First, check whether this request is coming from the USA
var ip = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
var req_from_USA = GeoLookup.country(ip) == "USA";
 
// Keep a reference to the existing function...
var oldQueryInventory = queryInventory;
// ... then put a new function in its place (which calls the existing one)
var queryInventory = function(query) {
   var options = {
       // Give requests from the USA a higher priority
       priority: req_from_USA ? 1 : 9, // lower number = higher priority
       // Don't let any request hang around for more than 10 seconds.
       expiration: 10 * 1000, // set in milliseconds
   };
   return limiter.schedule(options, oldQueryInventory, query);
};

node-limiter.p3.js

// Subscribe to change events from the named flag...
ldClient.on("update:" + LIMIT_FLAG_KEY, function(oldValue, newValue) {
   // ... and use them to update the limiter configuration.
   console.log(LIMIT_FLAG_KEY + " changed:", newValue, "(" + oldValue + ")");
   limiter.updateSettings({ maxConcurrent: newValue ? 100 : 10000 });
});

third-party-snippet.php

  <!-- Single-line “if” doesn’t need closing -->
	<?php if $this->checkFlag(“analytics-embed”, false): ?>
		<script src=... ></script>