Feature Management is a library for enabling/disabling features at runtime. Developers can use feature flags in simple use cases like conditional statement to more advanced scenarios like conditionally adding routes.
npm install @microsoft/feature-management
Feature management provides a way to develop and expose application functionality based on features. Many applications have special requirements when a new feature is developed such as when the feature should be enabled and under what conditions. This library provides a way to define these relationships, and also integrates into common JavaScript code patterns to make exposing these features possible.
Azure App Configuration Quickstart: A quickstart guide about how to integrate feature flags from Azure App Configuration into your JavaScript applications.
Feature Overview: This document provides a feature status overview.
Feature Reference: This document provides a full feature rundown.
You can use feature flags from the Azure App Configuration service, local files or any other sources. For more information, please go to Feature flag configuration.
#### Use feature flags from Azure App Configuration
The App Configuration JavaScript provider provides feature flags in as a Map object.
A builtin ConfigurationMapFeatureFlagProvider helps to load feature flags in this case.
``js`
import { load } from "@azure/app-configuration-provider";
import { FeatureManager, ConfigurationMapFeatureFlagProvider } from "@microsoft/feature-management";
const appConfig = await load("
const featureProvider = new ConfigurationMapFeatureFlagProvider(appConfig);
const featureManager = new FeatureManager(featureProvider);
const isAlphaEnabled = await featureManager.isEnabled("Alpha");
console.log("Feature Alpha is:", isAlphaEnabled);
#### Use feature flags from a json file
A sample JSON file with the following format can be used to load feature flags.
The JSON file can be read and parsed as an object as a whole.
A builtin ConfigurationObjectFeatureFlagProvider helps to load feature flags in this case.
Content of sample.json:`json`
{
"feature_management": {
"feature_flags": [
{
"id": "Alpha",
"description": "",
"enabled": true,
"conditions": {
"client_filters": []
}
}
]
}
}
Load feature flags from sample.json file.`js``
import { FeatureManager, ConfigurationObjectFeatureFlagProvider } from "@microsoft/feature-management";
const config = JSON.parse(await fs.readFile("path/to/sample.json"));
const featureProvider = new ConfigurationObjectFeatureFlagProvider(config);
const featureManager = new FeatureManager(featureProvider);
const isAlphaEnabled = await featureManager.isEnabled("Alpha");
console.log("Feature Alpha is:", isAlphaEnabled);
See code snippets under examples/ folder.
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