鑑於以下JSON對象：的Javascript合併/濾波器陣列
var posts = {
[0] : {
"name": "X",
"categories" : [1, 5, 6]
},
[1] : {
"name": "Y",
"categories" : [1, 5, 7]
}
}
我怎樣才能得到一個包含每個「類別」屬性值的單個陣列，無需重複？
在這種情況下，我想檢索類似
變種objCategories = [1，5，6，7];
像
var objCategories = {}; //create a map for all unique keys
Object.keys(posts).forEach(function(index){
var post = posts[ index ]; //get access to the object
post.categories.forEach(function(cat){
objCategories[ cat ] = cat;
});
});
objCategories = Object.keys(objCategories); //get only the arrays of categories and assign them back to objCategories for desired result
這將導致'TypeError：posts.forEach不是一個函數'，因爲它不是一個數組，它是一個對象。 – Svenskunganka
'posts'似乎是'object'給我.. – Rayon
@Svenskunganka現在再試 – gurvinder372
做
var posts = {
[0] : {
"name": "X",
"categories" : [1, 5, 6]
},
[1] : {
"name": "Y",
"categories" : [1, 5, 7]
}
}
// logic
var merged = []; // get all of the categories
for (let name in posts) { // loop through name
var post = posts[name]; // get post
merged = merged.concat(post.categories); // add categories
}
var unique = merged.filter(function(item, pos, self) { // filter duplicates
return self.indexOf(item) == pos;
});
console.log(unique);EXP：
這將收集所有類別
for (let name in posts) { // loop through name
var post = posts[name]; // get post
merged = merged.concat(post.categories); // add categories
}
結果將是
[1, 5, 6, 1, 5, 7]
那麼這將過濾掉重複：
var unique = merged.filter(function(item, pos, self) { // filter duplicates
return self.indexOf(item) == pos;
});
結果是」
[1, 5, 6, 7]
您通過對象必須循環：
var posts = {
[0] : {
"name": "X",
"categories" : [1, 5, 6]
},
[1] : {
"name": "Y",
"categories" : [1, 5, 7]
}
}
var objCategories = [];
Object.values(posts).forEach(post => {
post.categories.forEach(c => {
if (objCategories.indexOf(c) === -1) {
objCategories.push(c);
}
})
});
console.log(objCategories);在開啓了ES6的環境中，你可以使用一組和減少
let objCategories = [...new Set(Object.values(posts).reduce((a,b) => a.concat(b.categories), []))];
let posts = {
[0]: {
"name": "X",
"categories": [1, 5, 6]
},
[1]: {
"name": "Y",
"categories": [1, 5, 7]
}
};
let cats = [...new Set(Object.values(posts).reduce((a, b) => a.concat(b.categories), []))];
console.log(cats);使用減少和foreach：
var posts = {
[0] : {
"name": "X",
"categories" : [1, 5, 6]
},
[1] : {
"name": "Y",
"categories" : [1, 5, 7]
}
};
var result = Object.keys(posts).reduce(function (categories, key) {
posts[key].categories.forEach(function (category) {
if (categories.indexOf(category) === -1) {
categories.push(category);
}
});
return categories;
}, []);
console.log(result);
請學習之間的差[對象（https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer）和[陣列（HTTPS：/ /developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array）。你對'posts'的定義很奇怪。 – str
我投票結束這個問題作爲題外話，因爲問題顯示輸入和輸出格式，但沒有任何努力的跡象。這使得質疑一個要求，而不是一個問題陳述 – Rajesh
你可以參考以下鏈接：** [基於屬性的組]（https://stackoverflow.com/questions/31688459/group-array-items-using-object）* *和** [刪除數組中的重複項]（https://stackoverflow.com/questions/9229645/remove-duplicates-from-javascript-array）**並玩弄（*合併*）以獲得最終解決方案。 – Rajesh