JavaScript：删除共享相同属性值的对象的重复项

JavaScript: Remove duplicates of objects sharing same property value

提问by Lauren F

I have an array of objects that I would like to trim down based on a specific key:valuepair. I want to create an array that includes only one object per this specific key:valuepair. It doesn't necessarily matter which object of the duplicates is copied to the new array.

我有一组对象，我想根据特定的key:value对来修剪这些对象。我想创建一个数组，其中每个特定key:value对只包含一个对象。将重复项的哪个对象复制到新数组并不重要。

For example, I want to trim based on the priceproperty of arrayWithDuplicates, creating a new array that only includes one of each value:

例如，我想根据 的price属性进行修剪arrayWithDuplicates，创建一个仅包含每个值之一的新数组：

var arrayWithDuplicates = [
  {"color":"red", 
    "size": "small",
    "custom": {
      "inStock": true,
      "price": 10
    }
  },
  {"color":"green", 
    "size": "small",
    "custom": {
      "inStock": true,
      "price": 30
    }
  },
  {"color":"blue", 
    "size": "medium",
    "custom": {
      "inStock": true,
      "price": 30
    }
  },
  {"color":"red", 
    "size": "large",
    "custom": {
      "inStock": true,
      "price": 20
    }
  }
];

Would become:

会成为：

var trimmedArray = [
  {"color":"red", 
    "size": "small",
    "custom": {
      "inStock": true,
      "price": 10
    }
  },
  {"color":"green", 
    "size": "small",
    "custom": {
      "inStock": true,
      "price": 30
    }
  },
  {"color":"red", 
    "size": "large",
    "custom": {
      "inStock": true,
      "price": 20
    }
  }
];

Is there a JavaScript or Angular function that would loop through and do this?

是否有 JavaScript 或 Angular 函数可以循环执行此操作？

EDIT: The property to filter on is nested within another property.

编辑：要过滤的属性嵌套在另一个属性中。

采纳答案by user3335966

You can use underscorefor this:

您可以为此使用下划线：

//by size:
var uSize = _.uniqBy(arrayWithDuplicates, function(p){ return p.size; });

//by custom.price;
var uPrice = _.uniqBy(arrayWithDuplicates, function(p){ return p.custom.price; });

回答by Tamas Hegedus

This function removes duplicate values from an array by returning a new one.

此函数通过返回一个新值从数组中删除重复值。

function removeDuplicatesBy(keyFn, array) {
    var mySet = new Set();
    return array.filter(function(x) {
        var key = keyFn(x), isNew = !mySet.has(key);
        if (isNew) mySet.add(key);
        return isNew;
    });
}

var values = [{color: "red"}, {color: "blue"}, {color: "red", number: 2}];
var withoutDuplicates = removeDuplicatesBy(x => x.color, values);
console.log(withoutDuplicates); // [{"color": "red"}, {"color": "blue"}]

So you could use it like

所以你可以像这样使用它

var arr = removeDuplicatesBy(x => x.custom.price, yourArrayWithDuplicates);

回答by yvesmancera

I don't think there's a built-in function in Angular, but it isn't hard to create one:

我认为 Angular 中没有内置函数，但创建一个并不难：

function removeDuplicates(originalArray, objKey) {
  var trimmedArray = [];
  var values = [];
  var value;

  for(var i = 0; i < originalArray.length; i++) {
    value = originalArray[i][objKey];

    if(values.indexOf(value) === -1) {
      trimmedArray.push(originalArray[i]);
      values.push(value);
    }
  }

  return trimmedArray;

}

Usage:

用法：

removeDuplicates(arrayWithDuplicates, 'size');

Returns:

返回：

[
    {
        "color": "red",
        "size": "small"
    },
    {
        "color": "blue",
        "size": "medium"
    },
    {
        "color": "red",
        "size": "large"
    }
]

And

和

removeDuplicates(arrayWithDuplicates, 'color');

Returns:

返回：

[
    {
        "color": "red",
        "size": "small"
    },
    {
        "color": "green",
        "size": "small"
    },
    {
        "color": "blue",
        "size": "medium"
    }
]

回答by gilly3

Use Array.filter(), keeping track of values by using an Objectas a hash, and filtering out any items whose value is already contained in the hash.

使用Array.filter()，通过将Object用作散列来跟踪值，并过滤掉其值已包含在散列中的任何项目。

function trim(arr, key) {
    var values = {};
    return arr.filter(function(item){
        var val = item[key];
        var exists = values[val];
        values[val] = true;
        return !exists;
    });
}

回答by Mukesh Ranjan

You can use lodashto remove duplicate objects:

您可以使用lodash删除重复的对象：

 import * as _ from 'lodash';
  _.uniqBy(data, 'id');

Here 'id' is your unique identifier

这里“ id”是您的唯一标识符

回答by sliter

Try the following function:

试试下面的函数：

function trim(items){
    const ids = [];
    return items.filter(item => ids.includes(item.id) ? false : ids.push(item.id));
}

回答by sudha priya

for (let i = 0; i < arrayWithDuplicates.length; i++) {
     for (let j = i + 1; j < arrayWithDuplicates.length; j++) {
       if (arrayWithDuplicates[i].name === students[j].name) {
          arrayWithDuplicates.splice(i, 1);
       }
     }
    }

this will work perfectly...and this will delete first repeated array.
To delete last repeated array we only have to change
 arrayWithDuplicates.splice(i, 1) ; into
 arrayWithDuplicates.splice(j, 1);

回答by Souvik Basu

Simple solution although not the most performant:

简单的解决方案虽然不是最高效的：

var unique = [];
duplicates.forEach(function(d) {
    var found = false;
    unique.forEach(function(u) {
        if(u.key == d.key) {
            found = true;
        }
    });
    if(!found) {
        unique.push(d);
    }
});

回答by yureka

using lodashyou can filter it out easily

使用lodash您可以轻松过滤掉它

the first parameter will be your array and second will be your field with duplicates

第一个参数将是您的数组，第二个参数将是您的重复字段

_.uniqBy(arrayWithDuplicates, 'color')

it will return an array with unique value

它将返回一个具有唯一值的数组

回答by Praveen M P

Here is the typescript way

这是打字稿方式

    public removeDuplicates(originalArray:any[], prop) {
    let newArray = [];
    let lookupObject = {};

    originalArray.forEach((item, index) => {
        lookupObject[originalArray[index][prop]] = originalArray[index];
    });

    Object.keys(lookupObject).forEach(element => {
        newArray.push(lookupObject[element]);
    });
    return newArray;
}

And

和

let output = this.removeDuplicates(yourArray,'color');