Functions

import {addCoordinateTransforms} from 'ol/proj';
Registers coordinate transform functions to convert coordinates between the source projection and the destination projection. The forward and inverse functions convert coordinate pairs; this function converts these into the functions used internally which also handle extents and coordinate arrays.
Name Type Description source
ProjectionLike Source projection.
destination
ProjectionLike Destination projection.
forward
function The forward transform function (that is, from the source projection to the destination projection) that takes a
Coordinate
as argument and returns the transformedCoordinate
.inverse
function The inverse transform function (that is, from the destination projection to the source projection) that takes a
Coordinate
as argument and returns the transformedCoordinate
. If the transform function can only transform less dimensions than the input coordinate, it is supposeed to return a coordinate with only the length it can transform. The other dimensions will be taken unchanged from the source. 
import {addEquivalentProjections} from 'ol/proj';
Registers transformation functions that don't alter coordinates. Those allow to transform between projections with equal meaning.
Name Type Description projections
Array<Projection> Projections.

import {addProjection} from 'ol/proj';
Add a Projection object to the list of supported projections that can be looked up by their code.
Name Type Description projection
Projection Projection instance.

import {clearUserProjection} from 'ol/proj';
Clear the user projection if set.

import {equivalent} from 'ol/proj';
Checks if two projections are the same, that is every coordinate in one projection does represent the same geographic point as the same coordinate in the other projection.
Name Type Description projection1
Projection Projection 1.
projection2
Projection Projection 2.
Returns:
Equivalent.

import {fromLonLat} from 'ol/proj';
Transforms a coordinate from longitude/latitude to a different projection.
Name Type Description coordinate
Coordinate Coordinate as longitude and latitude, i.e. an array with longitude as 1st and latitude as 2nd element.
projection
ProjectionLike  undefined Target projection. The default is Web Mercator, i.e. 'EPSG:3857'.
Returns:
Coordinate projected to the target projection.

import {get} from 'ol/proj';
Fetches a Projection object for the code specified.
Name Type Description projectionLike
ProjectionLike Either a code string which is a combination of authority and identifier such as "EPSG:4326", or an existing projection object, or undefined.
Returns:
Projection object, or null if not in list.

import {getPointResolution} from 'ol/proj';
Get the resolution of the point in degrees or distance units. For projections with degrees as the unit this will simply return the provided resolution. For other projections the point resolution is by default estimated by transforming the
point
pixel to EPSG:4326, measuring its width and height on the normal sphere, and taking the average of the width and height. A custom function can be provided for a specific projection, either by setting thegetPointResolution
option in theProjection
constructor or by usingsetGetPointResolution
to change an existing projection object.Name Type Description projection
ProjectionLike The projection.
resolution
number Nominal resolution in projection units.
point
Coordinate Point to find adjusted resolution at.
units
Units  undefined Units to get the point resolution in. Default is the projection's units.
Returns:
Point resolution.

import {getTransform} from 'ol/proj';
Given the projectionlike objects, searches for a transformation function to convert a coordinates array from the source projection to the destination projection.
Name Type Description source
ProjectionLike Source.
destination
ProjectionLike Destination.
Returns:
Transform function.

import {getUserProjection} from 'ol/proj';
Get the projection for coordinates supplied from and returned by API methods. Note that this method is not yet a part of the stable API. Support for user projections is not yet complete and should be considered experimental.
Returns:
The user projection (or null if not set).

import {setUserProjection} from 'ol/proj';
Set the projection for coordinates supplied from and returned by API methods. This includes all API methods except for those interacting with tile grids.
Name Type Description projection
ProjectionLike The user projection.

import {toLonLat} from 'ol/proj';
Transforms a coordinate to longitude/latitude.
Name Type Description coordinate
Coordinate Projected coordinate.
projection
ProjectionLike  undefined Projection of the coordinate. The default is Web Mercator, i.e. 'EPSG:3857'.
Returns:
Coordinate as longitude and latitude, i.e. an array with longitude as 1st and latitude as 2nd element.

import {transform} from 'ol/proj';
Transforms a coordinate from source projection to destination projection. This returns a new coordinate (and does not modify the original).
See
transformExtent
for extent transformation. See the transform method ofGeometry
and its subclasses for geometry transforms.Name Type Description coordinate
Coordinate Coordinate.
source
ProjectionLike Source projectionlike.
destination
ProjectionLike Destination projectionlike.
Returns:
Coordinate.

import {transformExtent} from 'ol/proj';
Transforms an extent from source projection to destination projection. This returns a new extent (and does not modify the original).
Name Type Description extent
Extent The extent to transform.
source
ProjectionLike Source projectionlike.
destination
ProjectionLike Destination projectionlike.
stops
number  undefined Number of stops per side used for the transform. By default only the corners are used.
Returns:
The transformed extent.

import {useGeographic} from 'ol/proj';
Use geographic coordinates (WGS84 datum) in API methods. This includes all API methods except for those interacting with tile grids.
Type Definitions

ProjectionLike{Projection} {string} {undefined}

A projection as
Projection
, SRS identifier string or undefined. 
A transform function accepts an array of input coordinate values, an optional output array, and an optional dimension (default should be 2). The function transforms the input coordinate values, populates the output array, and returns the output array.