# Time of day routing with Functions

A very common use case for Functions is implementing time of day routing in your application. For example, varying your application's response to incoming calls based on what time and day a customer is calling, or which path to take in an IVR being written with [Twilio Studio](/docs/studio).

Before getting deeper into the example, first create a Service and Function so that you have a place to write and test your Function code.

## Create and host a Function

Before you run any of the examples on this page, create a Function and paste the example code into it. You can create a Function in the Twilio Console or by using the [Serverless Toolkit](/docs/labs/serverless-toolkit).

## Console

If you prefer a UI-driven approach, complete these steps in the Twilio Console:

1. Log in to the [Twilio Console](https://1console.twilio.com) and navigate to **Develop > Functions & Assets**. If you're using the *legacy* Console, open the [**Functions** tab](https://www.twilio.com/console/functions/overview).
2. Functions are contained within **Services**. Click **[Create Service](https://www.twilio.com/console/functions/overview/services)** to create a new **[Service](/docs/serverless/functions-assets/functions/create-service)**.
3. Click **Add +** and select **Add Function** from the dropdown.
4. The Console creates a new [protected](/docs/serverless/functions-assets/visibility) Function that you can rename. The filename becomes the URL path of the Function.
5. Copy one of the example code snippets from this page and paste the code into your newly created Function. You can switch examples by using the dropdown menu in the code rail.
6. Click **Save**.
7. Click **Deploy All** to build and deploy the Function. After deployment, you can access your Function at `https://<service-name>-<random-characters>-<optional-domain-suffix>.twil.io/<function-path>`\
   For example: `test-function-3548.twil.io/hello-world`.

## Serverless Toolkit

The [Serverless Toolkit](/docs/labs/serverless-toolkit) lets you develop locally, deploy projects, and perform other tasks through the [Twilio CLI](/docs/twilio-cli/quickstart).

1. From the CLI, run `twilio serverless:init <YOUR-SERVICE-NAME> --empty` to bootstrap your local environment.
2. Go to your new project directory using `cd <YOUR-SERVICE-NAME>`.
3. In the `/functions` directory, create a JavaScript file whose name reflects the purpose of the Function. For example, `sms-reply.protected.js` for a [protected](/docs/serverless/functions-assets/visibility) Function intended to handle incoming SMS.
4. Add the code example of your choice to the file and save it. Note that a Function can only export a single handler. You need to create separate files to run or deploy multiple examples at once.

After you save the Function code, you can test it locally (and optionally tunnel requests to it using a tool like [ngrok](https://ngrok.com/)), or deploy it.

### Run your Function in local development

Run `twilio serverless:start` from your CLI to start the project locally. The Function(s) in your project are accessible from `http://localhost:3000/sms-reply`

* If you want to test a Function as a [Twilio webhook](/docs/usage/webhooks/getting-started-twilio-webhooks), run: `twilio phone-numbers:update <your Twilio phone number> --sms-url "http://localhost:3000/sms-reply"`\
  This automatically generates an ngrok tunnel from Twilio to your locally running Function, so you can start sending texts to it. You can apply the same process but with the `voice-url` flag instead to test with [Twilio Voice](/docs/voice).
* If your code does *not* connect to Twilio Voice or Messages as a webhook, start your dev server and start an ngrok tunnel in the same command with the `ngrok` flag. For example: `twilio serverless:start --ngrok=""`

### Deploy your Function

To deploy your Function and have access to live url(s), run `twilio serverless:deploy` from your CLI. This deploys your Function(s) to Twilio under a development Environment by default, where they can be accessed from:

`https://<service-name>-<random-characters>-dev.twil.io/<function-path>`

For example: `https://incoming-sms-examples-3421-dev.twil.io/sms-reply`

You can now invoke your Function with HTTP requests, configure it as the [webhook](/docs/usage/webhooks/getting-started-twilio-webhooks) for a Twilio phone number, call it from a Twilio Studio [**Run Function** Widget](/docs/studio/widget-library/run-function), and more.

## Date and time dependent responses

One potential implementation is to simply respond to callers with a different message depending on the day and time that they are calling. Suppose your business is located on the East coast of the US, and has hours 9am-5pm, Monday-Friday. Calls on those days and between those hours should receive a response indicating that the business is open, while calls on the weekend or outside of business hours should receive a closed message.

This can be accomplished purely by leveraging built-in JavaScript methods, courtesy of the Internationalization API's [Intl.DateTimeFormat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat) object. By providing the specific `timeZone` of your business in the [accepted tz format](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones), you can derive the current day and time, and perform any necessary logic to determine your response.

To test this code out, paste the code into the Function that you just created earlier, and set it as the **A Call Comes In** webhook handler for the Twilio phone number you wish to test. The following instructions will show you how to do so.

> \[!WARNING]
>
> Remember that methods such as `new Date()` return the local time of the machine that your deployed code is being executed on, *not* your local time. Functions are typically executing in the UTC time zone. This is why all examples are using [Intl.DateTimeFormat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat) instead of just the `Date` object directly.

> \[!NOTE]
>
> We highly recommend using built-in objects such as [Intl.DateTimeFormat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat) to implement your application logic, or the [date-fns](https://date-fns.org/) library if you need more robust date utilities.
>
> [Moment.js](https://momentjs.com/docs/#/-project-status/) is end of life and should *not* be used for handling time zone shifts, formatting, etc.

```js title="Responding to a call based on date and time of call"
exports.handler = (context, event, callback) => {
  // Create a new voice response object
  const twiml = new Twilio.twiml.VoiceResponse();
  // Grab the current date and time. Note that this is the local time where the
  // Function is being executed, not necessarily the time zone of your business!
  const now = new Date();
  // Print the timezone of the instance that's running this code
  const functionTz = Intl.DateTimeFormat().resolvedOptions().timeZone;
  console.log(`This Function is being executed in the ${functionTz} time zone`);
  // You should see: 'This Function is being executed in the UTC time zone'

  // Configure Intl.DateTimeFormat to return a date in the specified
  // time zone and in this format for parsing, for example: 'Monday, 18'
  const formatOptions = {
    hour: 'numeric',
    hour12: false,
    weekday: 'long',
    timeZone: 'America/New_York',
  };
  const formatter = new Intl.DateTimeFormat('en-US', formatOptions);

  // Get the current time and day of the week for your specific time zone
  const formattedDate = formatter.format(now).split(', ');
  const day = formattedDate[0]; // ex. 'Monday'
  const hour = Number(formattedDate[1]); // ex. 18
  // Since we're given days as strings, we can use Array.includes to check
  // against a list of days we want to consider the business closed
  const isWeekend = ['Sunday', 'Saturday'].includes(day);

  // Here the business is considered open M-F, 9am-5pm Eastern Time
  const isOpen = !isWeekend && hour >= 9 && hour < 17;
  // Modify the stated voice response depending on whether the business is open or not
  twiml.say(`Business is ${isOpen ? 'Open' : 'Closed'}`);
  return callback(null, twiml);
};
```

## Set a Function as a webhook

For your Function to react to incoming SMS or voice calls, it must be set as a [webhook](/docs/usage/webhooks) for your Twilio number. There are a variety of methods to set a Function as a webhook:

![Setting a Function as a Messaging webhook using the webhook dropdown option.](https://docs-resources.prod.twilio.com/bf4eae4ac40fe7d47003a93bca295d5c232e0b372358e73ceff931fee3ccdc4f.png)

## Time of day routing in a Studio Flow

This logic can also be applied in the context of a [Studio Flow](/docs/studio), such as in an [IVR](/docs/glossary/what-is-ivr). For example, a Function can return an `isOpen` property as a Boolean (or a more advanced data structure if you like), and a subsequent [Split Based On... Widget](/docs/studio/widget-library/split-based-on) could then perform pattern matching on that value to determine how the Flow should advance. The following code sample would generate a Boolean that can be consumed in a Split Based On... Widget by referencing `{{widgets.<widget-name>.parsed.isOpen}}`.

Check out [this section](/docs/serverless/functions-assets/quickstart/run-function-studio-widget#consume-the-output-of-the-run-function-widget) of the [Run Function widget example](/docs/serverless/functions-assets/quickstart/run-function-studio-widget) to better understand consuming parsed values and generally how to execute this sample via the [Run Function](/docs/studio/widget-library/run-function) widget.

```js title="Support time of day routing in Twilio Studio"
// !mark(25,26,27)
exports.handler = (context, event, callback) => {
  // Grab the current date and time. Note that this is the local time where the
  // Function is being executed, not necessarily the time zone of your business!
  const now = new Date();
  // Configure Intl.DateTimeFormat to return a date in the specified
  // time zone and in this format for parsing, for example: 'Monday, 18'
  const formatOptions = {
    hour: 'numeric',
    hour12: false,
    weekday: 'long',
    timeZone: 'America/New_York',
  };
  const formatter = new Intl.DateTimeFormat('en-US', formatOptions);

  // Get the current time and day of the week for your specific time zone
  const formattedDate = formatter.format(now).split(', ');
  const day = formattedDate[0]; // ex. 'Monday'
  const hour = Number(formattedDate[1]); // ex. 18
  // Since we're given days as strings, we can use Array.includes to check
  // against a list of days we want to consider the business closed
  const isWeekend = ['Sunday', 'Saturday'].includes(day);

  // Here the business is considered open M-F, 9am-5pm Eastern Time
  const isOpen = !isWeekend && hour >= 9 && hour < 17;
  // Return isOpen in an object that can be parsed and then
  // used by the Split Based On... Widget for Flow routing
  return callback(null, { isOpen });
};
```