A simple Ajax utility to send and receive requests with vanilla JavaScript

Ajax.js

function Ajax(url, fn) {
	var request = new XMLHttpRequest();
	request.open('GET', url, true);
	request.onload = function() {
		if (request.status >= 200 && request.status < 400) {
			var data = JSON.parse(request.responseText);
			fn(data);
		} else {
			console.log("Error. Server connection OK.", request.responseText);
		}
	};
	request.onerror = function() {
		console.log("Error. Server connection FAIL.", request.responseText);
	};
	request.send();
};

function Post(url, fn, params) {
	var request = new XMLHttpRequest();
	request.open('POST', url, true);
        request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	request.onload = function() {
		if (request.status >= 200 && request.status < 400) {
			var data = JSON.parse(request.responseText);
			fn(data);
		} else {
			console.log("Error. Server connection OK.", request.responseText);
		}
	};
	request.onerror = function() {
		console.log("Error. Server connection FAIL.", request.responseText);
	};
	request.send(params);
};