javascript - Filter nested object properties based on value

Question

Consider the following data:

const state = {
  tasks: {
    'ID1': {
      name: "Go to shop",
      completed: false,
    },
    'ID2': {
      name: "Get bananas",
      completed: true,
    },
    'ID3': {
      name: "Get apples",
      completed: false,
    }
  }
}

To retrieve only the tasks that have completed set to true the follwoing code can be used:

function getCompletedTasks(state) {
  let tasks = {}

  Object.keys(state.tasks).forEach((key) => {
    let task = state.tasks[key]

    if (task.completed) tasks[key] = task
  })

  return tasks
}

I was wondering if there's a better way than manually creating a new array with let tasks = {}? I've looked at map but I'm not really sure this can help. I'm a newbie, just trying to understand if there's a cleaner better way.

Answer 1

You can use Object.entries to get an array of entries, filter it by whether the value's completed property is truthy, then turn it back into an object with Object.fromEntries:

const state = {
  tasks: {
    'ID1': {
      name: "Go to shop",
      completed: false,
    },
    'ID2': {
      name: "Get bananas",
      completed: true,
    },
    'ID3': {
      name: "Get apples",
      completed: false,
    }
  }
}

function getCompletedTasks(state) {
  return Object.fromEntries(
    Object.entries(state.tasks).filter(([, val]) => val.completed)
  );
}

console.log(getCompletedTasks(state));