Check if properties of a TypeScript object are all empty

Question

I have an object that looks like this:

objectProp = {
  property1: [],
  property2: [],
}

I want to check if all properties(that are string arrays) if this object are null and return true. I am for some reason stuck. How can I do this? I am using "target": "es2015"

I tried this but does not work:

 if (!Object.keys(this.objectProp).every(array => array.length > 0)) {
      console.log('all are empety');
    }

Does this answer your question? [How to Check if Arrays in a Object Are All Empty?](https://stackoverflow.com/questions/39919560/how-to-check-if-arrays-in-a-object-are-all-empty) — Heretic Monkey, Feb 25 '20 at 14:59

palaѕн · Answer 1 · 2020-02-25T14:59:25.843

5

You need to use Object.values(this.objectProp) instead of Object.keys(this.objectProp) for this to work. As Object.keys method returns an array of a given object's own enumerable property names and Object.values method returns an array of a given object's own enumerable property values, which is actually what you are looking for.

let objectProp = {
  property1: [],
  property2: [],
}

console.log(Object.keys(objectProp))

console.log(Object.values(objectProp))

For Es2015, you can try this:

let obj = {
  property1: [],
  property2: [],
}

// Log is print only when all arrays are empty
if (Object.keys(obj).map(e => obj[e]).every(a => a.length === 0)) {
  console.log('all are empty');
}

edited Feb 25 '20 at 14:59

answered Feb 25 '20 at 14:39

palaѕн

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it would be a nice solution but i am using "target": "es2015" – Kathrine Hanson Feb 25 '20 at 14:42
You can use the simple polyfill then mentioned [here](https://github.com/tc39/proposal-object-values-entries/blob/master/polyfill.js) – palaѕн Feb 25 '20 at 14:45
@KathrineHanson Instead of adding that to every answer after the answer has been written, please edit your question and add it there... – Heretic Monkey Feb 25 '20 at 14:57

Harun Yilmaz · Accepted Answer · 2020-02-25T14:54:18.293

2

By using Object.keys() you can do it as following

var objectProp = {
  property1: [],
  property2: [],
}

if(Object.keys(objectProp).every(key => objectProp[key] && objectProp[key].length === 0)){
  console.log('All is empty')
}

edited Feb 25 '20 at 14:54

answered Feb 25 '20 at 14:39

Harun Yilmaz

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it would be a nice solution but i am using "target": "es2015" – Kathrine Hanson Feb 25 '20 at 14:42
Updated as you requested – Harun Yilmaz Feb 25 '20 at 14:44
Slight logic bug, but the OP did the same `!Object.value` & `>0` with every, means if a single one is not empty, it will print `All is empty`,.. It should be `Object.values` & `<=0` with every. Or alternatively ! and some. – Keith Feb 25 '20 at 14:46
I think you did not understand what i want. I want to check if ALL properties of the object are empty. Not just if only one is empty but ALL. – Kathrine Hanson Feb 25 '20 at 14:48
@Keith u are right that it does not work but the way you wrote it I do not understand. can u write it completely? thanks. – Kathrine Hanson Feb 25 '20 at 14:51
Updated again. Please have a look at – Harun Yilmaz Feb 25 '20 at 14:55

score 2 · Answer 3 · answered Feb 25 '20 at 14:43

2

You should use Object.values as follow:

if (!Object.values(this.objectProp).every(({length}) => Boolean(length))) {
  console.log('all are empety');
}

answered Feb 25 '20 at 14:43

Ele

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it would be a nice solution but i am using "target": "es2015" – Kathrine Hanson Feb 25 '20 at 14:49

score 0 · Answer 4 · answered Feb 25 '20 at 14:57

Most answers seem to have missed the part about your logic been slightly wrong. They will say empty, if only single item is empty,. This is because the logic is !every > 0 But switching this logic to every <= 0 will get what you want.

eg.

The below example will return true, true for the broken version. But true, false for the fixed one.

var objectProp = {
  property1: [],
  property2: [],
};

var objectProp2 = {
  property1: [],
  property2: [],
  property3: ['not empty']
};


function allIsEmptyBroken(objectProp) {
  return (!Object.keys(objectProp).every(key => objectProp[key] && objectProp[key].length > 0));
}

function allIsEmptyFixed(objectProp) {
  return (Object.keys(objectProp).every(key => objectProp[key] && objectProp[key].length <= 0));
}


console.log('allIsEmptyBroken');
console.log(allIsEmptyBroken(objectProp));
console.log(allIsEmptyBroken(objectProp2));

console.log('allIsEmptyFixed');
console.log(allIsEmptyFixed(objectProp));
console.log(allIsEmptyFixed(objectProp2));

Check if properties of a TypeScript object are all empty

4 Answers4