До сих пор мы научились использовать чистые функции, чтобы избежать побочных эффектов в программе. Кроме того, мы видели, что значение наличия функции зависит только от ее входных аргументов. Это только начало. Как следует из названия, функциональное программирование сосредоточено вокруг теории функций. Было бы разумно иметь возможность передавать их в качестве аргументов другим функциям и возвращать функцию из другой функции. Функции считаются <code>First Class Objects</code> в JavaScript, что означает, что они могут использоваться как любой другой объект. Они могут быть сохранены в переменных, сохранены в объекте или переданы как аргументы функции. Начнем с некоторых простых функций массива, которые являются методами прототипа объекта массива. В этом упражнении мы смотрим на <code>Array.prototype.map()</code> или более просто на <code>map</code> . Помните, что метод <code>map</code> - это способ перебора каждого элемента в массиве. Он создает новый массив (без изменения исходного) после применения функции обратного вызова для каждого элемента.
В массиве <code>watchList</code> хранятся объекты с информацией о нескольких фильмах. Используйте <code>map</code> чтобы вытащить заголовок и рейтинг из <code>watchList</code> и сохранить новый массив в переменной <code>rating</code> . Код в редакторе в настоящее время использует цикл <code>for</code> для этого, замените функциональность цикла на ваше выражение <code>map</code> .
- text: Your code should use the <code>map</code> method.
testString: assert(code.match(/\.map/g));
- text: <code>rating</code> should equal <code>[{"title":"Inception","rating":"8.8"},{"title":"Interstellar","rating":"8.6"},{"title":"The Dark Knight","rating":"9.0"},{"title":"Batman Begins","rating":"8.3"},{"title":"Avatar","rating":"7.9"}]</code>.
testString: assert(JSON.stringify(rating) === JSON.stringify([{"title":"Inception","rating":"8.8"},{"title":"Interstellar","rating":"8.6"},{"title":"The Dark Knight","rating":"9.0"},{"title":"Batman Begins","rating":"8.3"},{"title":"Avatar","rating":"7.9"}]));
"Actors": "Leonardo DiCaprio, Joseph Gordon-Levitt, Ellen Page, Tom Hardy",
"Plot": "A thief, who steals corporate secrets through use of dream-sharing technology, is given the inverse task of planting an idea into the mind of a CEO.",
"Language": "English, Japanese, French",
"Country": "USA, UK",
"Awards": "Won 4 Oscars. Another 143 wins & 198 nominations.",
"Writer": "Jonathan Nolan (screenplay), Christopher Nolan (screenplay), Christopher Nolan (story), David S. Goyer (story), Bob Kane (characters)",
"Actors": "Christian Bale, Heath Ledger, Aaron Eckhart, Michael Caine",
"Plot": "When the menace known as the Joker wreaks havoc and chaos on the people of Gotham, the caped crusader must come to terms with one of the greatest psychological tests of his ability to fight injustice.",
"Language": "English, Mandarin",
"Country": "USA, UK",
"Awards": "Won 2 Oscars. Another 146 wins & 142 nominations.",
"Writer": "Bob Kane (characters), David S. Goyer (story), Christopher Nolan (screenplay), David S. Goyer (screenplay)",
"Actors": "Christian Bale, Michael Caine, Liam Neeson, Katie Holmes",
"Plot": "After training with his mentor, Batman begins his fight to free crime-ridden Gotham City from the corruption that Scarecrow and the League of Shadows have cast upon it.",
"Language": "English, Urdu, Mandarin",
"Country": "USA, UK",
"Awards": "Nominated for 1 Oscar. Another 15 wins & 66 nominations.",
"Actors": "Sam Worthington, Zoe Saldana, Sigourney Weaver, Stephen Lang",
"Plot": "A paraplegic marine dispatched to the moon Pandora on a unique mission becomes torn between following his orders and protecting the world he feels is his home.",
"Language": "English, Spanish",
"Country": "USA, UK",
"Awards": "Won 3 Oscars. Another 80 wins & 121 nominations.",
"Actors": "Leonardo DiCaprio, Joseph Gordon-Levitt, Ellen Page, Tom Hardy",
"Plot": "A thief, who steals corporate secrets through use of dream-sharing technology, is given the inverse task of planting an idea into the mind of a CEO.",
"Language": "English, Japanese, French",
"Country": "USA, UK",
"Awards": "Won 4 Oscars. Another 143 wins & 198 nominations.",
"Writer": "Jonathan Nolan (screenplay), Christopher Nolan (screenplay), Christopher Nolan (story), David S. Goyer (story), Bob Kane (characters)",
"Actors": "Christian Bale, Heath Ledger, Aaron Eckhart, Michael Caine",
"Plot": "When the menace known as the Joker wreaks havoc and chaos on the people of Gotham, the caped crusader must come to terms with one of the greatest psychological tests of his ability to fight injustice.",
"Language": "English, Mandarin",
"Country": "USA, UK",
"Awards": "Won 2 Oscars. Another 146 wins & 142 nominations.",
"Writer": "Bob Kane (characters), David S. Goyer (story), Christopher Nolan (screenplay), David S. Goyer (screenplay)",
"Actors": "Christian Bale, Michael Caine, Liam Neeson, Katie Holmes",
"Plot": "After training with his mentor, Batman begins his fight to free crime-ridden Gotham City from the corruption that Scarecrow and the League of Shadows have cast upon it.",
"Language": "English, Urdu, Mandarin",
"Country": "USA, UK",
"Awards": "Nominated for 1 Oscar. Another 15 wins & 66 nominations.",
"Actors": "Sam Worthington, Zoe Saldana, Sigourney Weaver, Stephen Lang",
"Plot": "A paraplegic marine dispatched to the moon Pandora on a unique mission becomes torn between following his orders and protecting the world he feels is his home.",
"Language": "English, Spanish",
"Country": "USA, UK",
"Awards": "Won 3 Oscars. Another 80 wins & 121 nominations.",
