Let‘s try creating a deeper tree structure. This time we have 4 separate arrays each containing lists, videos, boxarts, and bookmarks respectively. Each object has a parent id, indicating its parent. We want to build an array of list objects, each with a name and a videos array. The videos array will contain the video‘s id, title, bookmark time, and smallest boxart url. In other words we want to build the following structure:
[ { "name": "New Releases", "videos": [ { "id": 65432445, "title": "The Chamber", "time": 32432, "boxart": "http://cdn-0.nflximg.com/images/2891/TheChamber130.jpg" }, { "id": 675465, "title": "Fracture", "time": 3534543, "boxart": "http://cdn-0.nflximg.com/images/2891/Fracture120.jpg" } ] }, { "name": "Thrillers", "videos": [ { "id": 70111470, "title": "Die Hard", "time": 645243, "boxart": "http://cdn-0.nflximg.com/images/2891/DieHard150.jpg" }, { "id": 654356453, "title": "Bad Boys", "time": 984934, "boxart": "http://cdn-0.nflximg.com/images/2891/BadBoys140.jpg" } ] } ]
Note: please make sure when creating objects (both lists and videos) that you add properties in the same order as above. This doesn‘t impact the correctness of your code, but the verifier expects properties to be created in this order.
function() { var lists = [ { "id": 5434364, "name": "New Releases" }, { "id": 65456475, name: "Thrillers" } ], videos = [ { "listId": 5434364, "id": 65432445, "title": "The Chamber" }, { "listId": 5434364, "id": 675465, "title": "Fracture" }, { "listId": 65456475, "id": 70111470, "title": "Die Hard" }, { "listId": 65456475, "id": 654356453, "title": "Bad Boys" } ], boxarts = [ { videoId: 65432445, width: 130, height:200, url:"http://cdn-0.nflximg.com/images/2891/TheChamber130.jpg" }, { videoId: 65432445, width: 200, height:200, url:"http://cdn-0.nflximg.com/images/2891/TheChamber200.jpg" }, { videoId: 675465, width: 200, height:200, url:"http://cdn-0.nflximg.com/images/2891/Fracture200.jpg" }, { videoId: 675465, width: 120, height:200, url:"http://cdn-0.nflximg.com/images/2891/Fracture120.jpg" }, { videoId: 675465, width: 300, height:200, url:"http://cdn-0.nflximg.com/images/2891/Fracture300.jpg" }, { videoId: 70111470, width: 150, height:200, url:"http://cdn-0.nflximg.com/images/2891/DieHard150.jpg" }, { videoId: 70111470, width: 200, height:200, url:"http://cdn-0.nflximg.com/images/2891/DieHard200.jpg" }, { videoId: 654356453, width: 200, height:200, url:"http://cdn-0.nflximg.com/images/2891/BadBoys200.jpg" }, { videoId: 654356453, width: 140, height:200, url:"http://cdn-0.nflximg.com/images/2891/BadBoys140.jpg" } ], bookmarks = [ { videoId: 65432445, time: 32432 }, { videoId: 675465, time: 3534543 }, { videoId: 70111470, time: 645243 }, { videoId: 654356453, time: 984934 } ]; return lists.map(function(list) { return { name: list.name, videos: videos. filter(function(video) { return video.listId === list.id; }). concatMap(function(video) { return Array.zip( bookmarks.filter(function(bookmark) { return bookmark.videoId === video.id; }), boxarts.filter(function(boxart) { return boxart.videoId === video.id; }). reduce(function(acc,curr) { return acc.width * acc.height < curr.width * curr.height ? acc : curr; }), function(bookmark, boxart) { return { id: video.id, title: video.title, time: bookmark.time, boxart: boxart.url }; }); }) }; }); }
[Javascript] bukld 'SQL' like object tree
原文：http://www.cnblogs.com/Answer1215/p/5621702.html