callback function example vanilla js

gistfile1.txt

var beverages = ['juice', 'soda', 'beer']
var func = function (thirsty, array, callback) {
  array.push(thirsty);
	var first = array[array.length - 1]
	return callback(first);
}


func('water', beverages, function (param) {
			return param
})

//will return water