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Compare 2 arrays of objects and add a property to the object with the matching id

March 27, 2023

`I have two arrays of objects like as below. I want to compare the ids of the two arrays and return isSomeProperty with boolean value.

const arr1 = [
{ id: 001, name: 'abc' },
{ id: 002, name: 'def' },
{ id: 003, name: 'ghi' },
{ id: 004, name: 'jkl' },
{ id: 005, name: 'mno' }
];

const arr2 = [
{ id: 001, name: 'abc' },
{ id: 002, name: 'def' }
];

arr1.forEach((item1) => {
    arr2.forEach((item2) => {
if (item1.id === item2.id) {
return {
...item1,
isSomeProperty: true;
}
} else {
return {
...item1,
isSomeProperty: false;
}
}
});
});
return arr1;

Is there a way to avoid using two forEach loops and done in an efficient way.

Expected Output:

const arr1 = [  
{ id: 001, name: 'abc', isSomeProperty: true },  
{ id: 002, name: 'def', isSomeProperty: true },  
{ id: 003, name: 'ghi', isSomeProperty: false },  
{ id: 004, name: 'jkl', isSomeProperty: false },  
{ id: 005, name: 'mno', isSomeProperty: false } 
];

>Solution :

const arr1 = [
  { id: 001, name: 'abc' },
  { id: 002, name: 'def' },
  { id: 003, name: 'ghi' },
  { id: 004, name: 'jkl' },
  { id: 005, name: 'mno' }
];

const arr2 = [
  { id: 001, name: 'abc' },
  { id: 002, name: 'def' }
];

const result = arr1.map(item1 => {
  const item2 = arr2.find(item2 => item1.id === item2.id);
  return {
    ...item1,
    isSomeProperty: !!item2 // convert item2 to a boolean value
  };
});

console.log(result);