Rocket.Chat/app/emoji/client/function-isSet.js

// http://stackoverflow.com/a/26990347 function isSet() from Gajus
export const isSet = function(fn) {
	let value;
	try {
		value = fn();
	} catch (e) {
		value = undefined;
	}
	return value !== undefined;
};

export const isSetNotNull = function(fn) {
	let value;
	try {
		value = fn();
	} catch (e) {
		value = null;
	}
	return value !== null && value !== undefined;
};