unleash.unleash/docs/guides/custom-acitvation-strategy.md

---
id: custom_activation_strategy
title: Custom Activation Strategy
---

Even though Unleash comes with a few powerful [activation strategies](activation-strategies.md) there might be scenarios where you would like to extend Unleash with your own custom strategies.

### Example: TimeStamp Strategy

In this example we want to define an activation strategy offers a scheduled release of a feature toggle. This means that we want the feature toggle to be activated after a given date and time.

#### Define custom strategy

First we need to "define" our new strategy. To add a new "Strategy", open the Strategies tab from the sidebar.

![timestamp_create_strategy](assets/timestamp_create_strategy.png)

We name our strategy `TimeStamp` and add one required parameter of type string, which we call `enableAfter`.

#### Use custom strategy

After we have created the strategy definition, we can now decide to use that activation strategy for our feature toggle.

![timestamp_use_strategy](assets/timestamp_use_strategy.png)

In the example we want to use our custom strategy for the feature toggle named `demo.TimeStampRollout`.

#### Client implementation

All official client SDK's for Unleash provides abstractions for you to implement support for custom strategies.

> Before you have provided support for the custom strategy; the client will return false, because it does not understand the activation strategy.

In Node.js the implementation for the `TimeStampStrategy` would be:

```javascript
const moment = require('moment');

class TimeStampStrategy extends Strategy {
  constructor() {
    super('TimeStamp');
  }

  isEnabled(parameters, context) {
    const enableAfterTimeStamp = moment(parameters.enableAfter);
    return moment().isAfter(enableAfterTimeStamp);
  }
}
```

In the example implementation we make use of the library called moment to parse the timestamp and verify that current time is after the specified `enabledAfter` parameter.

All parameter injected to the strategy are handled as `string` objects. This means that the strategies needs to parse it to a more suitable format. In this example we make use of the [moment](https://github.com/moment/moment) library. This library makes it also very convenient to check if we have passed the date/time specified via the `enabledAfter` parameter.

We also have to remember to register the custom strategy when initializing the Unleash client. Full working code example:

```javascript
const moment = require('moment');
const { Strategy, initialize, isEnabled } = require('unleash-client');

class TimeStampStrategy extends Strategy {
  constructor() {
    super('TimeStamp');
  }

  isEnabled(parameters, context) {
    const enableAfterTimeStamp = moment(parameters.enableAfter);
    return moment().isAfter(enableAfterTimeStamp);
  }
}

const instance = initialize({
  url: 'http://unleash.herokuapp.com/api/',
  appName: 'unleash-demo',
  instanceId: '1',
  strategies: [new TimeStampStrategy()],
});

instance.on('ready', () => {
  setInterval(() => {
    console.log(isEnabled('demo.TimeStampRollout'));
  }, 1000);
});
```