proj4/lib/Proj.js

Proj4js is a JavaScript library to transform point coordinates from one coordinate system to another, including datum transformations.

var parseCode = require("./parseCode");
var extend = require('./extend');
var projections = require('./projections');
var deriveConstants = require('./deriveConstants');

function Projection(srsCode,callback) {
  if (!(this instanceof Projection)) {
    return new Projection(srsCode);
  }
  callback = callback || function(error){
    if(error){
      throw error;
    }
  };
  var json = parseCode(srsCode);
  if(typeof json !== 'object'){
    callback(srsCode);
    return;
  }
  var modifiedJSON = deriveConstants(json);
  var ourProj = Projection.projections.get(modifiedJSON.projName);
  if(ourProj){
    extend(this, modifiedJSON);
    extend(this, ourProj);
    this.init();
    callback(null, this);
  }else{
    callback(srsCode);
  }
}
Projection.projections = projections;
Projection.projections.start();
module.exports = Projection;