Question

我正在尝试从数组内部和对象内部的数组中检索所有唯一值

var items = [
{
  colors:['white', 'black'],
  fruits:['apple, banana']
},

{
  colors:['yellow', 'black'],
  fruits:['mango, blueberry'],
},
...
]

const property = 'colors'
const values = this.distinct(this.items.map(item => item[property].map(elem => elem))

我希望这些值返回具有每个颜色值的数组，如下所示：

['black','white','yellow']

但是它不起作用，我也不知道为什么

Answer 1

flatMap对象数组，以提取每个colors子数组，传递给Set构造函数以进行重复数据删除，然后将Set返回为数组：

var items = [{
  colors:['white', 'black'],
  fruits:['apple, banana']
},{
  colors:['yellow', 'black'],
  fruits:['mango, blueberry'],
}];
const colorsSet = new Set(
  items.flatMap(item => item.colors)
);
const uniques = [...colorsSet];
console.log(uniques);

Answer 2

reduce可用于遍历数组并将颜色分配为累加器对象的键：

const result = items.reduce((a, {colors})=> {
    colors.forEach(cl => a[cl] = 1);
    return a;
}, {})
console.log(Object.keys(result));

或单行方式：

Object.keys(items.reduce((a, {colors})=> (colors.forEach(cl => a[cl] = 1) , a), {}));

Read more about reduce method

一个例子：

let items = [
    {
        colors: ['white', 'black'],
        fruits: ['apple, banana']
    },

    {
        colors: ['yellow', 'black'],
        fruits: ['mango, blueberry'],
    }
]

const result = items.reduce((a, {colors})=> {
    colors.forEach(cl => a[cl] = 1);
    return a;
},{})
console.log(Object.keys(result));

const oneLine = Object.keys(items.reduce((a, {colors})=> 
    (colors.forEach(cl => a[cl] = 1) , a), {}));
console.log(oneLine);

Javascript-从对象内部的数组获取唯一值

2 个答案: