Fill a empty value of a key-value pair using the previous value

Fill a empty value of a key-value pair with the last value of the previous key.

myitems = {
 'items1': [{first:true, second:false}, {first:true, second:true}],
 'items2': [], //should be filled with {first:true, second:true}
 'items3': [], //should be filled with {first:true, second:true}
 'items4': [{first:true, second:false}, {first:true, second:true}],
 'items5': [{first:false, second:true}],
 'items6': [], //should be filled with {first:false, second:true}
 'items7': [{first:true, second:true}],
}

>Solution :

You can do something like this to achieve that..

let lastValue = null;

for (const key in myitems) {
  if (myitems[key].length === 0) {
    if (lastValue !== null) {
      myitems[key] = [lastValue];
    }
  } else {
    lastValue = myitems[key][myitems[key].length - 1];
  }
}