javascript coordinate conversions between 900913(3857) - 4326(lat lon)

degrees2meters.js

var degrees2meters = function(lon,lat) {
  var x = lon * 20037508.34 / 180;
  var y = Math.log(Math.tan((90 + lat) * Math.PI / 360)) / (Math.PI / 180);
  y = y * 20037508.34 / 180;
  return [x, y]
}
//test
lon= -77.035974
lat = 38.898717

console.log(degrees2meters(lon,lat))

// should result in: -8575605.398444, 4707174.018280

meters2degress.js

var meters2degress = function(x,y) {
  var lon = x *  180 / 20037508.34 ;
  //thanks magichim @ github for the correction
  var lat = Math.atan(Math.exp(y * Math.PI / 20037508.34)) * 360 / Math.PI - 90; 
  return [lon, lat]
}
//test
x= -8575605.398444
y = 4707174.018280

console.log(meters2degress(x,y))

//should result in: -77.035974, 38.898717