osm2geojson-lite/README.md

a lightweight yet faster osm (either in xml or in json formats) to geojson convertor - 4x faster than xmldom + osmtogeojson in most situations - implemented in pure JavaScript without any 3rd party dependency

osm2geojson-lite
============

A lightweight (not as lightweight as xml2geojson though) yet faster convertor for [OSM](http://openstreetmap.org) [data](http://wiki.openstreetmap.org/wiki/OSM_XML) whatever in XML or JSON formats to [GeoJSON](http://www.geojson.org/) - much faster (the more complex the data source is, the more performance advantages it posesses) than osmtogeojson in most situations - implemented in pure JavaScript without any 3rd party dependency.

History
-----
An internal function inside [query-geo-boundary](https://www.npmjs.com/package/query-geo-boundary) → stripped out to handle OSM XML only [xml2geojson-lite](https://www.npmjs.com/package/xml2geojson-lite) → this library that supports both OSM XML and OSM/Overpass JSON

Changelog:
-----
* Late 2018: this repository was created and the initial version was pushed to github - almost around specific usages for myself.
* 2019-2025: quite a few contributors had fixed quite a few bugs and also contributed some good ideas - thanks for their efforts!
* 2025-03-03: fixed a few bugs around non-*Polygon features processing and convert it to a pure TypeScript project (codes published to [NPM](https://npmjs.org/) have become TSC compiled from now on).

Usage
-----

### As a Node.JS Library

Installation:

    $ npm install osm2geojson-lite

Usage:

```js
    const osm2geojson = require('osm2geojson-lite');
    let geojson = osm2geojson(osm, opts);
```

### In the Browser
```html
    <script src='your/path/to/osm2geojson-lite.js'/>
```
```js
    let geojson = osm2geojson(osm, opts);
```

API
---

### `osm2geojson(osm, opts)`

Converts OSM data (XML/JSON) to GeoJSON.

* `osm`: the OSM XML data in String, or OSM/Overpass JSON as object or in String
* `opts?`: optional, the options object, right now supports below properties/fields:
    - `completeFeature/allFeatures`:  the default value is `false`. When it's set to `true`, the returned geojson will include all elements that meet the specified conditions in `FeatureCollection` format; otherwise, only the bare geometry of the first `relation` element will be returned.
    - `renderTagged`: the default value is `false`. When it's set to `true`, the returned geojson will include all elements with tags (i.e., tagged) until `suppressWay` changes its behavior a bit; otherwise only the unreferenced ones get returned.
    - `suppressWay/excludeWay`: the default value is `true`. When it's set to `true`, the returned `FeatureCollection` will exclude all referenced `way`s even though they are tagged; otherwise the features of those `way`s will be included in the resulted result as well.


Performance
---
1. Workloads include the boundary XML and JSON of 4 administrive areas (zhucheng, hebei, tokyodo, usa)
2. Call each conversion for 100 rounds to mitigate the impacts of GC and other factors
3. For each script, run as many as times seperately and then calculate the average cost time (ACT for short)
4. The # listed in the table below are coarse lowest values of dividing the ACT of `osmtogeojson` by the one of this library
```
$ cd bench
$ node o2gl-bench.js
$ node otg-bench.js
```
1. XML
   
| zhucheng  | hebei    | tokyodo | usa  |
|-----------|----------|---------|------|
| >2.5x     | >4.0x    | >3.0x   | >3.0x|

2. Overpass JSON
   
| zhucheng  | hebei    | tokyodo | usa  |
|-----------|----------|---------|------|
| >2.5x     | >11.0x   | >7.0x   | >5.0x|


Correctness
---
You can copy the converted results to [geojsonlint](http://geojsonlint.com) for the correctness validation.  Up until now, `osm2geojson-lite` behaves pretty well with all the samples (also quite representative) in the `data` subfolers under `test` and `bench` directories, which also outperforms `osmtogeojson`. 

The client side example shipped along with this package, `test/index.html` ~~will automatically call `geojsonlint` validation service directly after each conversion, you can wait for a while to see the validation result after click the conversion button.~~ - because the CORS limitation, the direct post to geojsonlint was blocked, so I added a "copy to clipboard" button for you to ease the validation.

Node.JS version
---
  ES5/ES6 features
  
Dependencies
---
  - No 3rd party dependency

License
---
Copyleft

Collaborators
---
* tibetty
* HarelM