src/tree/patch.js
function keysIndexes(children, startIndex, endIndex) {
  var i, keys = Object.create(null), key;
  for (i = startIndex; i <= endIndex; ++i) {
    if (children[i]) {
      key = children[i].key;
      if (key !== undefined) {
        keys[key] = i;
      }
    }
  }
  return keys;
}
function keysIndexes(children, startIndex, endIndex) {
  var i, keys = Object.create(null), key;
  for (i = startIndex; i <= endIndex; ++i) {
    if (children[i]) {
      key = children[i].key;
      if (key !== undefined) {
        keys[key] = i;
      }
    }
  }
  return keys;
}
function keysIndexes ( children , startIndex , endIndex ) { var i , keys = Object . create ( null ) , key ; for ( i = startIndex ; i <= endIndex ; ++ i ) { if ( children [ i ] ) { key = children [ i ] . key ; if ( key !== undefined ) { keys [ key ] = i ; } } } return keys ; }
Returns indexes of keyed nodes.

@param  Array  children An array of nodes.
@return Object          An object of keyed nodes indexes.
Returns indexes of keyed nodes .