holyshit.js

var regex = /\[([^\.]*?)\.?([^\.\]]*)\]/g;
var input = "123 [VALUE] abc [234.VALUE] def [123.NONONO] xyz";

function getReplacement(firstGroup, secondGroup) {
	if (firstGroup && secondGroup == 'VALUE') {
		return new Promise(resolve => {
			resolve('XXX');
		});
	}

	if (!firstGroup && secondGroup == 'VALUE') {
		return new Promise(resolve => {
			resolve('YYY');
		});
	}

	return new Promise(resolve => {
		resolve('undefined');
	});
}

var captures = input.match(regex); // with global flag
async.each(captures, function (item, done) {
	const matchPerCapture = item.match(/\[([^\.]*?)\.?([^\.\]]*)\]/); // Without global flag
	const id = matchPerCapture[1];
	const attribute = matchPerCapture[2];
	getReplacement(id, attribute)
		.then(res => {
			input = input.replace(item, res);
			done();
		});
}, function () {
	console.log('finished replacing');
	console.log('result: ' + input);
});
console.log('end of file');