# @turf/point-on-line

# pointOnLine

Takes a [Point](http://geojson.org/geojson-spec.html#point) and a [LineString](http://geojson.org/geojson-spec.html#linestring) and calculates the closest Point on the (Multi)LineString.

**Parameters**

-   `lines` **([Geometry](http://geojson.org/geojson-spec.html#geometry) \| [Feature](http://geojson.org/geojson-spec.html#feature-objects)<([LineString](http://geojson.org/geojson-spec.html#linestring) \| [MultiLineString](http://geojson.org/geojson-spec.html#multilinestring))>)** lines to snap to
-   `pt` **([Geometry](http://geojson.org/geojson-spec.html#geometry) \| [Feature](http://geojson.org/geojson-spec.html#feature-objects)<[Point](http://geojson.org/geojson-spec.html#point)> | [Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)<[number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)>)** point to snap from
-   `units` **\[[string](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** can be degrees, radians, miles, or kilometers (optional, default `kilometers`)

**Examples**

```javascript
var line = turf.lineString([
    [-77.031669, 38.878605],
    [-77.029609, 38.881946],
    [-77.020339, 38.884084],
    [-77.025661, 38.885821],
    [-77.021884, 38.889563],
    [-77.019824, 38.892368]
]);
var pt = turf.point([-77.037076, 38.884017]);

var snapped = turf.pointOnLine(line, pt, 'miles');

//addToMap
var addToMap = [line, pt, snapped];
snapped.properties['marker-color'] = '#00f';
```

Returns **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<[Point](http://geojson.org/geojson-spec.html#point)>** closest point on the `line` to `point`. The properties object will contain three values: `index`: closest point was found on nth line part, `dist`: distance between pt and the closest point, `location`: distance along the line between start and the closest point.

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---

This module is part of the [Turfjs project](http://turfjs.org/), an open source
module collection dedicated to geographic algorithms. It is maintained in the
[Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create
PRs and issues.

### Installation

Install this module individually:

```sh
$ npm install @turf/point-on-line
```

Or install the Turf module that includes it as a function:

```sh
$ npm install @turf/turf
```