mcp23017_node_input.js
# ! /usr/local/bin/node
//
//	mcp23017_node_input.js
//
//					May/31/2017
//
// ------------------------------------------------------------------
function read_proc (wire)
{
	wire.readBytes(0x13, 1, function(err, res)
	{
	console.log (res)

	console.log (res[0].toString(16))
	console.log ("*** end ***")
	})
}

// ------------------------------------------------------------------
console.log ("*** start ***")
var i2c = require('i2c')
const address = 0x20
var wire = new i2c(address, {device: '/dev/i2c-1'})
	// point to your i2c address, debug provides REPL interface 

wire.writeBytes(0x01, [0xff], function(err, res)
	{
	wire.writeBytes(0x0d, [0xff], function(err, res)
		{
		read_proc (wire)
		})
	})

// ------------------------------------------------------------------