getDropboxToken.js

// About API:
// https://www.dropbox.com/developers/core/docs#oa2-authorize
// https://www.dropbox.com/developers/core/docs#oa2-token

var config = require('./config.json');
// OR...
// var config = {
// 	'appKey': 'xxxxxxxxxxxxxxx',
// 	'secretKey': 'xxxxxxxxxxxxxxx'
// };

var readline = require('readline');
var https = require('https');
var querystring = require('querystring');

// Show authrize page
var url = 'https://www.dropbox.com/1/oauth2/authorize?' +
	querystring.stringify({ response_type:'code', client_id:config.appKey });
console.log('Open and get auth code:\n\n', url, '\n');

// Get the auth code
var rl = readline.createInterface(process.stdin, process.stdout);
rl.question('Input the auth code: ', openRequest);  // defined below

function openRequest(authCode) {
	var req = https.request({
		headers: { 'Content-Type': 'application/json' },
		hostname: 'api.dropbox.com',
		method: 'POST',
		path: '/1/oauth2/token'
	}, reseiveResponse);  // defined below

	// ################################
	// Send code
	// (maybe wrong...)
	var data = JSON.stringify({
		code: authCode,
		grant_type: 'authorization_code',
		client_id: config.appKey,
		client_secret: config.secretKey
	});
	req.write(data);
	// ################################
	req.end();

	console.log('Request:');
	console.log('--------------------------------');
	console.log(data);
	console.log('--------------------------------');
}

function reseiveResponse(res) {
	var response = '';
	res.on('data', function(chunk) { response += chunk; });

	// Show result
	res.on('end', function() {
		console.log('Response:');
		console.log('--------------------------------');
		console.log(response);  // "Missing client credentials"
		console.log('--------------------------------');
		process.exit();
	});
}

getDropboxTokenOnBrowser.js

console.assert(location.host==='api.dropbox.com');

var xhr = new XMLHttpRequest();
xhr.open('POST', '/1/oauth2/token');
xhr.onload = function(){ console.log(xhr.response); };  // "Missing client credentials"
xhr.send(JSON.stringify({
	code: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
	grant_type: 'authorization_code',
	client_id: 'xxxxxxxxxxxxxxx',
	client_secret: 'xxxxxxxxxxxxxxx'
}));