function replaceChildren(element, newChildren) {
  removeChildren(element);
  addChildren(element, newChildren);
}

function addChildren(element, children) {
  for (let child of children) {
    element.appendChild(child);
  }
}

function removeChildren(element) {
  while (element.lastChild) {
    element.removeChild(element.lastChild);
  }
}

function round(val, places = 0) {
  return Math.round(val * Math.pow(10, places)) / Math.pow(10, places);
}

function mapObject(obj, func) {
  return deepFreeze(Object.keys(obj).reduce((o, k) => ({ ...o, [k]: func(obj[k])}), {}));
}

function deepFreeze(object) {

  // Retrieve the property names defined on object
  var propNames = Object.getOwnPropertyNames(object);

  // Freeze properties before freezing self
  
  for (let name of propNames) {
    let value = object[name];

    object[name] = value && typeof value === "object" ? 
      deepFreeze(value) : value;
  }

  return Object.freeze(object);
}

function showBuilding(key) {
  let count = belongings[key].count;
  let name = count == 1 ? buildings[key].name : buildings[key].plural;
  return count + " " + name.toLowerCase()
}

function capitalize(string) {
  return string[0].toUpperCase() + string.slice(1)
}

function weekday() {
  return ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"][(new Date()).getDay()];
}

function weightedSelect(weights) {
  const total = weights.reduce((x,y) => x+y, 0);
  const rand = Math.random() * total;
  let counter = weights[0];
  let index = 0;
  while (counter < rand) {
    index += 1;
    counter += weights[index];
  }

  return index;
}