Check if a file exists with it's http status (200) with a promise

httpStatus.js

window.httpStatus = (address) => {
	return new Promise( (resolve, reject) => {
		let client = new XMLHttpRequest();
		client.onload = function () {
			if (this.status === 200) resolve(this.status);
			if (this.status !== 200) reject(this.status);
		};
		client.open("HEAD", address, true);
		client.send();
	});
};