en.javascript.info/1-js/4-data-structures/8-array-iteration/1-rewrite-for-map/solution.md

//+ run
var arr = ["Есть", "жизнь", "на", "Марсе"];

*!*
var arrLength = arr.map(function(item) {
  return item.length;
});
*/!*

alert( arrLength ); // 4,5,2,5