Osrm-text-instructions NPM

OSRM Text Instructions

OSRM Text Instructions is a Node.js library that transforms route data generated by OSRM into localized turn instructions to be displayed visually or read aloud by a text-to-speech engine. OSRM Text Instructions is the basis of guidance instructions in osrm-frontend, the Mapbox Directions API, and the Mapbox Navigation SDK.

Global: Text instructions are available in over a dozen languages via Transifex. Abbreviations and advanced grammatical transformations are available in some languages.
Customizable: Flexible options allow you to format and tweak the results to your liking.
Cross-platform: A data-driven approach facilitates implementations in other programming languages. OSRM Text Instructions is also available in Swift and Objective-C (for iOS, macOS, tvOS, and watchOS) and in Java (for Android and Java SE).
Well-tested: A data-driven test suite ensures compatibility across languages and platforms.

Usage

var version = 'v5';
var osrmTextInstructions = require('osrm-text-instructions')(version);

response.legs.forEach(function(leg) {
  leg.steps.forEach(function(step) {
    instruction = osrmTextInstructions.compile('en', step, options)
  });
});

If you are unsure if the user's locale is supported by osrm-text-inustrctions, use @mapbox/locale-utils for finding the best fitting language.

Parameters `require('osrm-text-instructions')(version)`

parameter	required?	values	description
`version`	required	`v5`	Major OSRM version

Parameters `compile(language, step, options)`

parameter	required?	values	description
`language`	required	`en` `de` `zh-Hans` `fr` `nl` `ru` and more	Compiling instructions for the selected language code.
`step`	required	OSRM route step object	The RouteStep as it comes out of OSRM
`options`	optional	Object	See below

Options

key	type	description
`legCount`	integer	Number of legs in the route
`legIndex`	integer	Zero-based index of the leg containing the step; together with `legCount`, this option determines which waypoint the user has arrived at
`formatToken`	function	Function that formats the given token value after grammaticalization and capitalization but before the value is inserted into the instruction string; useful for wrapping tokens in markup
`waypointName`	string	Optional custom name for the leg's destination, replaces `"your {nth} destination"`

formatToken takes two parameters:

token: A string that indicates the kind of token, such as way_name or direction
value: A grammatical string for this token, capitalized if the token appears at the beginning of the instruction

and returns a string.

Architecture

index.js contains the main transformation logic in JavaScript.
languages/ contains the localization files, including raw format strings, abbreviation files, and grammar rules.
languages.js loads the localizations and contains some localization-related helper functions.
test/ contains data-driven integration tests and test fixtures for all supported languages.