Here is the state of my App:

 const [state, setState] = useState({
    priceType: 0,
    recurrenceType: 0,
    start_date: '',
    end_date: '',
    minCapacity: 0,
    maxCapacity: 0,
    price: 0,
    min: 0,
    max: 0,
    days: []
});

Here is the code of condition in which I am trying to achive, if any property of the state has null value then return true otherwise return false.

const isNullish = Object.values(state).every(value => {
        if (value==='' && value===0 && value === []) {
          return true;
        }
        return false;
      });
console.log(isNullish)
console.log(state)

But the chalenge is whenever I execute that code in my app it returns false although the properties has no value.Below is the console output of above code:

false
SpecialPrice.jsx:124 {priceType: 0, recurrenceType: 0, start_date: '', end_date: '', 
minCapacity: 0, …}
days: []
end_date: ""
max: 0maxCapacity: 0
min: 0
minCapacity: 0
price: 0
priceType: 0
recurrenceType: 0
start_date: ""
[[Prototype]]: Object
SpecialPrice.jsx:129 []

For better understanding I have attached a screenshot here:

CodePudding user response：

First problem:

The logic is asserting a value is equal to three different other values with the logical AND (&&), which will just about always be false.

value === '' && value === 0 && value === []

A value can never be strictly equal to a string '' and a number 0, and an empty array [].

You could assert on the inverse of each though, checking for inequality.

value !== '' && value !== 0 && value !== []

Second problem:

The last condition, value === [], even if value currently had the value [], [] === [] always evaluates false, they are two object references and these can never be strictly equal.

const value = [];
console.log(value === []); // false
console.log([] === []);    // false

Solution

Use logical OR (||) instead to check each condition.

The final condition should first check if the value is an array and then check for 0 length, or use the Optional Chaining operator (basically to guard against undefined value values).

Example:

const isNullish = Object.values(state).every((value) => {
  return value === "" || value === 0 || (Array.isArray(value) && !value.length);
});

or

const isNullish = Object.values(state).every((value) => {
  return value === "" || value === 0 || !value?.length;
});

or since both '' and 0 are considered falsey values you can further simplify the conditionals.

const isNullish = Object.values(state).every((value) => {
  return !value || !value.length;
});

Falsey values include false, 0, -0, 0n, "" (and other empty strings), null, undefined, NaN.

const state = {
  priceType: 0,
  recurrenceType: 0,
  start_date: "",
  end_date: "",
  minCapacity: 0,
  maxCapacity: 0,
  price: 0,
  min: 0,
  max: 0,
  days: [],
  days2: undefined
};

const state2 = {
  priceType: 0,
  recurrenceType: 0,
  start_date: "",
  end_date: "",
  minCapacity: 0,
  maxCapacity: 0,
  price: 0,
  min: 0,
  max: 0,
  days: [3],
  days2: undefined
};

const isNullish = arr => Object.values(arr).every((value) => {
  return !value || !value.length;
});

console.log(isNullish(state));  // true
console.log(isNullish(state2)); // false

CodePudding user response：

.every is in this case not the right approach. With .every you check if every value is 0 or []. In your case not every value is 0 or [].

I would suggest you use .some

Something like this:

const isNullish = Object.values(state).some(x => x === 0 || x === [] || x === '');