September 19, 2020

How to check the Javascript object is empty or not?

In Javascript, there is no straight forward way to check javascript object is empty or not.

Like

var str1 = '';

if(!str1){
  // will run
}
console.log(!!str1); //false

var obj1 = {};
if(!obj1){
  //will not run
}
console.log(!!obj1) // true

If you see above, an empty string will be considered as a falsy value but the empty objects will not be considered as falsy value.

So, let’s see how we can check object is empty or not

Object.keys method

Object.keys method will return an array of keys in the object

var obj1 = {
    a:10
};

console.log(Object.keys(obj1));//["a"]

var obj2 = {}

console.log(Object.keys(obj2));//[]

console.log(Object.keys(obj1).length === 0);//length is not zero means object is not emppty

console.log(Object.keys(obj2).length === 0); // length is zero means object is empty

As you can see above we are using Object.keys method which returns an array of object keys.

On the array, we can check length of an array. If length is zero then the object is empty else object is not empty

Using for-in loop

we can use for in loop to check object is empty or not

var obj1 = {};
function isEmpty(obj1){
  let isObjectEmpty = true;
  for(let obj in obj1){
    if(obj1.hasOwnProperty(obj)){
        isObjectEmpty = false;
        break;
    }
  }
  return isObjectEmpty
  
}

console.log(isEmpty(obj1))

In the above code, we have created one function named as isEmpty which takes obj1 as a parameter.

In the function we are iterating over the object using a for-in loop, In that, we are checking any property present on an object or not, If present then we are returning false means object is not empty else is empty

If you are using any utility library kind of lodash then library provides inbuilt function like _.isEmpty which helps you to identify the object is empty or not

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