# @turf/nearest-point-on-line

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## nearestPointOnLine

Takes a [Point][1] and a [LineString][2] and calculates the closest Point on the (Multi)LineString.

### Parameters

*   `lines` **([Geometry][3] | [Feature][4]<([LineString][2] | [MultiLineString][5])>)** lines to snap to
*   `pt` **([Geometry][3] | [Feature][4]<[Point][1]> | [Array][6]<[number][7]>)** point to snap from
*   `options` **[Object][8]** Optional parameters (optional, default `{}`)

    *   `options.units` **[string][9]** 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.nearestPointOnLine(line, pt, {units: 'miles'});

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

Returns **[Feature][4]<[Point][1]>** closest point on the `line` to `point`. The properties object will contain four values: `index`: closest point was found on nth line part, `multiFeatureIndex`: closest point was found on the nth line of the `MultiLineString`, `dist`: distance between pt and the closest point, `location`: distance along the line between start and the closest point.

[1]: https://tools.ietf.org/html/rfc7946#section-3.1.2

[2]: https://tools.ietf.org/html/rfc7946#section-3.1.4

[3]: https://tools.ietf.org/html/rfc7946#section-3.1

[4]: https://tools.ietf.org/html/rfc7946#section-3.2

[5]: https://tools.ietf.org/html/rfc7946#section-3.1.5

[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

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---

This module is part of the [Turfjs project](https://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 single module individually:

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

Or install the all-encompassing @turf/turf module that includes all modules as functions:

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