javascript - 如何使用js查找对象数组中的重复数据？

Question

我有以下对象数组，例如

[  
   {  
      "id":"30772",
      "posimage":"/b/l/blue-shirt_1_1.jpg",
      "position":"Position Front",
      "tech":"Screen Print"
   },
   {  
      "id":"30771",
      "posimage":"/b/l/blue-shirt_3.jpg",
      "position":"Position Front",
      "tech":"Screen Print"
   },
   {  
      "id":"30772",
      "posimage":"/b/l/blue-shirt_1_1.jpg",
      "position":"Position Front",
      "tech":"Embroidery"
   },
   {  
      "id":"30771",
      "posimage":"/b/l/blue-shirt_3.jpg",
      "position":"Position Front",
      "tech":"Embroidery"
   }
]

这里我有重复的值，例如“id”:“30772”，“position”:“Position Front”我需要获取重复的位置，并且需要在警告框中给出，例如位置前面重复。

Answer 1

const items = [{  
  "id":"30772",
  "posimage":"/b/l/blue-shirt_1_1.jpg",
  "position":"Position Front",
  "tech":"Screen Print"
},
{  
  "id":"30771",
  "posimage":"/b/l/blue-shirt_3.jpg",
  "position":"Position Front",
  "tech":"Screen Print"
},
{  
  "id":"30772",
  "posimage":"/b/l/blue-shirt_1_1.jpg",
  "position":"Position Front",
  "tech":"Embroidery"
},
{  
  "id":"30771",
  "posimage":"/b/l/blue-shirt_3.jpg",
  "position":"Position Front",
  "tech":"Embroidery"
}]

items.forEach(item => {
    const result = items.filter(it => it.id === item.id)
        if (result.length > 1) {
            return 'duplicate value exists';
        } 
        return 'no duplicates';
 })