Create a Canvas as ImageOverlay to draw the Lat/Lon Graticule,

and show the grid tick label at the edges of the map.

Check out the demo.

Usage example

L.latlngGraticule({
    showLabel: true,
    dashArray: [5, 5],
    zoomInterval: [
        {start: 2, end: 3, interval: 30},
        {start: 4, end: 4, interval: 10},
        {start: 5, end: 7, interval: 5},
        {start: 8, end: 10, interval: 1}
    ]
}).addTo(map);

Options

• showLabel: Show the grid tick label at the edges of the map. Default true
• opacity: Opacity of the Graticule and Label. Default 1
• weight: The width of the graticule lines. Default 0.8
• color: The color of the graticule lines. Default #aaa
• font: Font Style for the tick label. Default 12px Verdana
• fontColor: Color of the tick label. Default #aaa
• dashArray: Used to achieve dashed lines. Default [0,0]
• sides: Used to name sides of the world. Default ['N', 'S', 'E', 'W']
• zoomInterval: Use different intervals in different zoom levels. You can set for both latitude and longitude lines as the example, or set different intervals for latitude and longitude like below:

  zoomInterval: {
    latitude: [
      {start: 4, end: 6, interval: 5},
      {start: 7, end: 20, interval: 1}
    ],
    longitude: [
      {start: 4, end: 6, interval: 10},
      {start: 7, end: 20, interval: 2}
    ]
  }

• Default:

  zoomInterval: [
    {start: 2, end: 2, interval: 40},
    {start: 3, end: 3, interval: 20},
    {start: 4, end: 4, interval: 10},
    {start: 5, end: 7, interval: 5},
    {start: 8, end: 20, interval: 1}
  ]

Special Options

Some of the projections (like Lambert) is no straight line, set those options to draw a polyline graticule.

• lngLineCurved: Interval of polyline. Deafult 0
• latLineCurved: Interval of polyline. Deafult 0

Check out the Lambert projection example.