# 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

In order to run any of the following examples, you will first need to create a Function into which you can paste the example code. You can create a Function using the Twilio Console or the [Serverless Toolkit](/docs/labs/serverless-toolkit) as explained below:

## Console

If you prefer a UI-driven approach, creating and deploying a Function can be done entirely using the Twilio Console and the following steps:

1. Log in to the Twilio Console and navigate to the [Functions tab](https://www.twilio.com/console/functions/overview). If you need an account, you can sign up for a free Twilio account [here](https://www.twilio.com/try-twilio)!
2. Functions are contained within **Services**. Create a **[Service](/docs/serverless/functions-assets/functions/create-service)** by clicking the **[Create Service](https://www.twilio.com/console/functions/overview/services)** button and providing a name such as *test-function*.
3. Once you've been redirected to the new Service, click the **Add +** button and select **Add Function** from the dropdown.
4. This will create a new [Protected](/docs/serverless/functions-assets/visibility) Function for you with the option to rename it. The name of the file will be path it is accessed from.
5. Copy any one of the example code snippets from this page that you want to experiment with, and paste the code into your newly created Function. You can quickly switch examples by using the dropdown menu of the code rail.
6. Click **Save** to save your Function's contents.
7. Click **Deploy All** to build and deploy the Function. After a short delay, your Function will be accessible from: `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) enables you with local development, project deployment, and other functionality via the [Twilio CLI](/docs/twilio-cli/quickstart). To get up and running with these examples using Serverless Toolkit, follow this process:

1. From the CLI, run `twilio serverless:init <your-service-name> --empty` to bootstrap your local environment.
2. Navigate into your new project directory using `cd <your-service-name>`
3. In the `/functions` directory, create a new JavaScript file that is named respective to 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. Populate the file using the code example of your choice and save. **Note** A Function can only export a single handler. You will want to create separate files if you want to run and/or deploy multiple examples at once.

Once your Function(s) code is written and saved, you can test it either by running it locally (and optionally tunneling requests to it via a tool like [ngrok](https://ngrok.com/)), or by deploying the Function and executing against the deployed url(s).

### Run your Function in local development

Run `twilio serverless:start` from your CLI to start the project locally. The Function(s) in your project will be 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 will automatically generate 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 if you want to test with [Twilio Voice](/docs/voice).
* If your code does *not* connect to Twilio Voice/Messages as a webhook, you can 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 will deploy 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`

Your Function is now ready to be invoked by HTTP requests, set as the [webhook](/docs/usage/webhooks/getting-started-twilio-webhooks) of a Twilio phone number, invoked by 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

In order for your Function to react to incoming SMS and/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, as detailed below:

![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 });
};
```