# slow-zone [![Build status](https://img.shields.io/circleci/project/github/banterability/slow-zone/main.svg)](https://circleci.com/gh/banterability/slow-zone/tree/main) [![Latest published version](https://img.shields.io/npm/v/slow-zone.svg)](https://www.npmjs.com/package/slow-zone) [![install size](https://packagephobia.com/badge?p=slow-zone)](https://packagephobia.com/result?p=slow-zone) A client & wrapper for CTA 'L' arrival data. ## Installation ```bash $ npm install slow-zone ``` ## Usage Make sure you have a [CTA Train Tracker API Key][1]. ```javascript import SlowZone from "slow-zone"; const client = new SlowZone({ apiKey: "afafafafafafafafafafafafafafafaf" }); ``` ### Arrivals #### `getArrivalsForStation(stationId, options?)` | Key | Value | | ----------- | ----------------------------------------------------------------------------------------------------------------------- | | `stationId` | A CTA station ID. See the [CTA API Documentation][2] for valid values. | | `options` | (Optional) Additional key/value pairs to pass through to the API. See the [CTA API documentation][2] for valid options. | Returns a Promise that either resolves with an array of objects, each describing a predicted train, or rejects with an error. ```javascript // Station: Logan Square client.getArrivalsForStation(41020) .then(arrivals => /* do something */) .catch(err => /* do something */); ``` #### `getArrivalsForStop(stopId, options?)` | Key | Value | | --------- | ----------------------------------------------------------------------------------------------------------------------- | | `stopId` | A CTA stop ID. See the [CTA API Documentation][2] for valid values. | | `options` | (Optional) Additional key/value pairs to pass through to the API. See the [CTA API documentation][2] for valid options. | Returns a Promise that either resolves with an array of objects, each describing a predicted train, or rejects with an error. ```javascript // Stop: Merchandise Mart (Southbound Platform) // Example uses options to only return Brown Line trains client.getArrivalsForStop(30091, {rt: "Brn"}) .then(arrivals => /* do something */) .catch(err => /* do something */); ``` ### Follow This Train #### `followTrain(runId)` | Key | Value | | ------- | ---------------------------------------------------------------------------- | | `runId` | A train run ID. Likely something you got from one of the above API requests. | Returns a Promise that either resolves with an array of objects, each describing a station stop, or rejects with an error. ```javascript sz.followTrain(410) .then(arrivals => /* do something */) .catch(err => /* do something */); ``` ### Response Structure Slow Zone reformats and decorates the response from the CTA API to speed up common tasks. Note that all fields may not be present on all responses. ```json { "destination": { "id": 30182, "name": "Midway" }, "location": { "latitude": 41.87685, "longitude": -87.6327, "heading": 269 }, "prediction": { "arrivalMinutes": 1, "arrivalString": "2:50 p.m.", "arrivalTime": "2014-10-07T21:50:27.000Z", "predictionAge": 3531786, "predictionTime": "2014-10-07T21:49:27.000Z" }, "route": { "class": "orange", "directionId": 5, "id": "Org", "name": "Orange", "run": 715 }, "station": { "id": 40160, "name": "LaSalle/Van Buren", "stop": { "id": 30031, "description": "Service at Inner Loop platform" } }, "status": { "approaching": true, "delayed": false, "faulty": false, "scheduled": false } } ``` #### Destination Data about the final destination of the predicted train: | Key | Value | | ------------------ | -------------------------------------------------------------- | | `destination.id` | (Integer) The GTFS station ID of the final destination station | | `destination.name` | (String) The name of the final destination station | #### Location Data about the predicted train's current location: | Key | Value | | -------------------- | ------------------------------------------ | | `location.latitude` | (Float) The current latitude of the train | | `location.longitude` | (Float) The current longitude of the train | | `location.heading` | (Integer) The current heading of the train | #### Prediction The prediction itself, in a number of formats: | Key | Value | | --------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | | `prediction.arrivalMinutes` | (Integer) The number of minutes until the train arrives at the station, rounded to the nearest minute | | `prediction.arrivalString` | (String) A user-friendly string of the time a train is expected to arrive. Formatted by [Dateline](https://github.com/banterability/dateline) | | `prediction.arrivalTime` | (Date) The date & time the train is predicted to arrive at the station | | `prediction.predictionAge` | (Integer) The number of seconds that have elapsed since the prediction was made | | `prediction.predictionTime` | (Date) The date & time when the prediction was generated | #### Route Data about the predicted train's route: | Key | Value | | ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- | | `route.class` | (String) The name of the route, lowercased for consistency | | `route.directionId` | (Integer) The directionality of the run. See the documentation for specifics, but as a general rule `1` is north & west, `5` is south and east | | `route.id` | (String) The CTA ID for the route | | `route.name` | (String) The name (color) of the route | | `route.run` | (Integer) A unique (that day) identifier for the run | #### Station Data about the station the prediction is relative to: | Key | Value | | -------------------------- | -------------------------------------------------------------------------------------------------------------------- | | `station.id` | (Integer) The GTFS station ID of the station the prediction is relative to | | `station.name` | (String) The name of the station the prediction is relative to | | `station.stop.id` | (Integer) The GTFS stop ID of the stop the prediction is relative to | | `station.stop.description` | (String) A description of the stop the prediction is relative to. Usually in the format "Service at \_\_\_ platform" | #### Status Flags that may affect the reliability or display context of a prediction: | Key | Value | | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | | `status.approaching` | (Boolean) Indicates that a train is approaching the station | | `status.delayed` | (Boolean) Indicates that a train has not reached the next waypoint by the time the prediction expected and it may no longer be accurate | | `status.faulty` | (Boolean) Indicates an issue with the train tracker system that prevents a prediction from being made | | `status.scheduled` | (Boolean) Indicates that a prediction is based on the preset schedule, not a train in motion. Frequently seen at the start & end of lines | ## Development | Command | Description | | ------------- | -------------------- | | `npm install` | Install dependencies | | `npm test` | Run tests | [1]: https://www.transitchicago.com/developers/traintrackerapply/ [2]: https://www.transitchicago.com/developers/ttdocs/