fetch the array of object based on property same using javascript

Question

I have two array of objects,arr1 and arr2

if taskId and id same then retreive from arr1

How to check based on property from arr1 and arr2 in javascript

var arr1= [
  {"name":"refresh task","memberIds":[981],"dueOn":"2022-08-30","taskId":19},
  {"name":"ref one","memberIds":[981,982],"dueOn":"2022-08-25","taskId":null}
]

var arr2 =[
{
"country": "IN", 
"tasks": [
    {id: 19, "name": "abc" },
    {id: 20, "name": "xyz" }
  ]
}
]
I tried 
var result = arr1.filter(e=>e.taskId===(arr2.map(i=>i.tasks.map(t=>t.id))

Expected Output
[
  {"name":"refresh task","memberIds":[981],"dueOn":"2022-08-30","taskId":19}
]

do a flatMap+map on arr2 to get a list of id. after that do a filter on arr1 and check if each element is include in the id list — cmgchess
– cmgchess, Commented Aug 2, 2022 at 19:16

Majed Badawi · Accepted Answer · 2022-08-02 21:21:09Z

2

Using Set, Array#flatMap, and [Array#map][3], get the list of task ids in arr2``
Using Array#filter, and Set#has, return the resulting array where taskId is in the above set

const
  arr1= [
    {"name":"refresh task", "memberIds":[981], "dueOn":"2022-08-30", "taskId":19},
    {"name":"ref one", "memberIds":[981,982], "dueOn":"2022-08-25", "taskId":null}
  ],
  arr2 =[
    { 
      "country": "IN", 
      "tasks": [ {"id": 19, "name": "abc"}, {"id": 20, "name": "xyz"} ]
    }
  ];

const taskIdSet = new Set(
  arr2.flatMap(({ tasks = [] }) => tasks.map(({ id }) => id))
);
const result = arr1.filter(({ taskId }) => taskIdSet.has(taskId));

console.log(result);

EDIT: To get "I have two arrays of objects, arr1, and arr2 if taskId and id not same then retrieve from arr2":

const
  arr1= [
    {"name":"refresh task", "memberIds":[981], "dueOn":"2022-08-30", "taskId":19},
    {"name":"ref one", "memberIds":[981,982], "dueOn":"2022-08-25", "taskId":null}
  ],
  arr2 =[
    { 
      "country": "IN", 
      "tasks": [ {"id": 19, "name": "abc"}, {"id": 20, "name": "xyz"} ]
    }
  ];

const taskIdSet = arr1.reduce((taskIdSet, { taskId }) => {
  if(taskId !== null) { taskIdSet.add(taskId); }
  return taskIdSet;
}, new Set);
const result = arr2
  .flatMap(({ tasks = [] }) => tasks)
  .filter(({ id }) => !taskIdSet.has(id));

console.log(result);

edited Aug 2, 2022 at 21:21

answered Aug 2, 2022 at 19:17

Majed Badawi

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5 Comments

codelearn Over a year ago

thanks for the solution, if i want get arr2 that are not matching with arr1 taskId , i.e(arr2 with no null and not same taskid and id)

codelearn Over a year ago

@can help how to do

codelearn Over a year ago

I have two array of objects,arr1 and arr2 if taskId and id not same then retreive from arr2 Expected Output [ {id: 20, "name": "xyz" } ]

Majed Badawi Over a year ago

@codelearn in this case, you need to save non-null task ids from arr1 in a set and do the filter on arr2

Majed Badawi Over a year ago

Answer updated.

k-devs · Accepted Answer · 2022-08-02 20:38:53Z

0

This works too:

var result = arr1.filter(e=>{
    for(let obj of arr2){ 
      for(let task of obj.tasks){
        return e.taskId === task.id; 
        }
    }
 })

answered Aug 2, 2022 at 20:38

k-devs

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