JavaScript Function for getting json data by Promise

function promiseFunction(url) {
	return new Promise( function(resolve, reject){
		var xhr = new XMLHttpRequest();
		xhr.open("GET", url, true);
		xhr.onload = function (e) {
			if (xhr.readyState === 4) {
				if (xhr.status === 200) {
					resolve(xhr.responseText);
				} else {
					reject(xhr.statusText);
				}
			}
		}
		xhr.onerror = function (e) {
			reject(xhr.statusText);
		};
		xhr.send(null);
		}).then(function(value){
			console.log(value);
		}).catch(function(value){
			console.log(value);
		});
}
promiseFunction('data.json');