Setting value to a complex object field by giving the object key as string

javascript-array-property-access.js

function propertyAccess(obj, key, value) {
  const sKey = key.replace(/\[/gi, '.').replace(/\]/gi, '').split('.')
  const current = sKey[0]
  const next = sKey.slice(1).join('.')
  if (sKey.length != 1) {
    return propertyAccess(obj[current], next, value)
  }
  if (value !== undefined) {
    obj[key] = value
  }
  return obj[key]
}

//--- Main ----
const myObject = {
  catalog: {
    products: [
      {
          id: 1,
          name: 'Shirt'
      },
      {
          id: 2,
          name: 'Jacket'
      }
    ]
  }
}

console.log( propertyAccess(myObject, 'catalog.products[1].id') ) // 2
propertyAccess(myObject, 'catalog.products[1].id', 3)
console.log( propertyAccess(myObject, 'catalog.products[1].id') ) // 3