this.checkableData = [{ key: 1 }, { key: 2 }, { key: 3 }, { key: 4 }];
this.keyProp = "key";
this.checked = [1, 2];
let checkableDataKeys = this.checkableData.map(item => {
  let keyProps = {};
  keyProps[item[this.keyProp]] = true;
  return keyProps;
});
console.log(checkableDataKeys);

this.checked.every(item => {
  console.log(checkableDataKeys[item]);
  return checkableDataKeys[item];
});

this.allChecked =
  checkableDataKeys.length > 0 &&
  this.checked.length > 0 &&
  this.checked.every(item => checkableDataKeys[item]);