JSFiddle - React, Tailwind, and code Playground

by Dmitri Ganenco

JavaScript

function compare(arr1, arr2) {

  const objMap = {};

  arr1.forEach((e1) => arr2.forEach((e2) => {
    if (e1 === e2) {
      objMap[e1] = objMap[e1] + 1 || 1;
    }
  }));
  console.log(Object.keys(objMap).map(e => Number(e)));
}


let array_a = [{
  a: 34,
  b: 78
}, {
  a: 55,
  b: 66
}];
let array_b = [{
  a: 34,
  b: 78
}, {
  a: 77,
  b: 989
}];

compare(array_a, array_b);