JSFiddle - React, Tailwind, and code Playground

JavaScript

example = {
	overview: undefined,
	aSyncFunction: function (callback) {
		
		setTimeout(function(){
			this.overview = {first: [{aa: 123, bb:000}], second: [{aa: 456, bb:999}]};
			if (callback) {
				callback();
			}
		}, 1000);
		
		return this;
	},
	
	otherFunction: function (data) {
		var result = false;
		
		this.aSyncFunction( function () {
			var available = this.overview[data.name];
			result = (_.find(available, function(obj) {
				return obj.aa === 123;
			})) ? true : false;
		}.bind(this));
		
		return result;
	}
};

console.log(example.otherFunction({name: 'first'}));