How to get key name when the value contains empty in an object with JavaScript?

To find keys with empty values in a JavaScript object, you can use Object.keys() combined with find() or filter(). This is useful for form validation or data cleaning.

Let's say we have the following object:

var details = {
   firstName: 'John',
   lastName: '',
   countryName: 'US'
};

Using Object.keys() with find()

To find the first key with an empty value, use Object.keys() along with find():

var details = {
   firstName: 'John',
   lastName: '',
   countryName: 'US'
};

var result = Object.keys(details).find(key => (details[key] === '' || details[key] === null));
console.log("The key is=" + result);

The key is=lastName

Using Object.keys() with filter() for Multiple Keys

To find all keys with empty values, use filter() instead:

var details = {
   firstName: 'John',
   lastName: '',
   email: null,
   countryName: 'US',
   city: ''
};

var emptyKeys = Object.keys(details).filter(key => (details[key] === '' || details[key] === null));
console.log("Keys with empty values:", emptyKeys);

Keys with empty values: [ 'lastName', 'email', 'city' ]

Handling Different Empty Types

You can check for various empty conditions like undefined, null, and empty strings:

var details = {
   firstName: 'John',
   lastName: '',
   email: null,
   age: undefined,
   countryName: 'US'
};

var emptyKeys = Object.keys(details).filter(key => {
   return details[key] === '' || details[key] === null || details[key] === undefined;
});

console.log("All empty keys:", emptyKeys);

All empty keys: [ 'lastName', 'email', 'age' ]

Conclusion

Use Object.keys() with find() to get the first empty key, or with filter() to get all empty keys. This approach handles null, undefined, and empty string values effectively.