function loadFile(src, success, error) {
		var xhr = new XMLHttpRequest();
		xhr.open('GET', src, true);
		xhr.onreadystatechange = function () {
			if (xhr.readyState == 4) {
				if (xhr.status < 400 && xhr.responseText) {
					success(xhr.responseText);
				} else {
					if (xhr.status >= 400) {
						error(FAILURE_MESSAGE(xhr.status, xhr.statusText));
					} else {
						error(FAILURE_EMPTY_MESSAGE);
					}
				}
			}
		};
		xhr.send(null);
	}
Loads the given file.

@param {string} src The URL or path of the source file to load.
@param {(result: string) => void} success
@param {(reason: string) => void} error