Answers for "how does array.from works on objects"

create object from array

// create object from array
const createObjectFromArray = (arr) => {
  let obj = {};
  for (let value of arr) {
    obj[value] = ++obj[value] || 1;
  }
  return obj;
};

find an object from array of objects javascript

function getByValue2(arr, value) {

  var result  = arr.filter(function(o){return o.b == value;} );

  return result? result[0] : null; // or undefined

}