Is Object Empty

Is object empty?

I'm assuming that by empty you mean "has no properties of its own".

// Speed up calls to hasOwnProperty
var hasOwnProperty = Object.prototype.hasOwnProperty;

function isEmpty(obj) {

    // null and undefined are "empty"
    if (obj == null) return true;

    // Assume if it has a length property with a non-zero value
    // that that property is correct.
    if (obj.length > 0)    return false;
    if (obj.length === 0)  return true;

    // If it isn't an object at this point
    // it is empty, but it can't be anything *but* empty
    // Is it empty?  Depends on your application.
    if (typeof obj !== "object") return true;

    // Otherwise, does it have any properties of its own?
    // Note that this doesn't handle
    // toString and valueOf enumeration bugs in IE < 9
    for (var key in obj) {
        if (hasOwnProperty.call(obj, key)) return false;
    }

    return true;
}

Examples:

isEmpty(""), // true
isEmpty(33), // true (arguably could be a TypeError)
isEmpty([]), // true
isEmpty({}), // true
isEmpty({length: 0, custom_property: []}), // true

isEmpty("Hello"), // false
isEmpty([1,2,3]), // false
isEmpty({test: 1}), // false
isEmpty({length: 3, custom_property: [1,2,3]}) // false

If you only need to handle ECMAScript5 browsers, you can use Object.getOwnPropertyNames instead of the hasOwnProperty loop:

if (Object.getOwnPropertyNames(obj).length > 0) return false;

This will ensure that even if the object only has non-enumerable properties isEmpty will still give you the correct results.

How do I test for an empty JavaScript object?

ECMA 5+:

// because Object.keys(new Date()).length === 0;
// we have to do some additional check
obj // null and undefined check
&& Object.keys(obj).length === 0
&& Object.getPrototypeOf(obj) === Object.prototype

Note, though, that this creates an unnecessary array (the return value of keys).

Pre-ECMA 5:

function isEmpty(obj) {
  for(var prop in obj) {
    if(Object.prototype.hasOwnProperty.call(obj, prop)) {
      return false;
    }
  }

  return JSON.stringify(obj) === JSON.stringify({});
}

jQuery:

jQuery.isEmptyObject({}); // true

lodash:

_.isEmpty({}); // true

Underscore:

_.isEmpty({}); // true

Hoek

Hoek.deepEqual({}, {}); // true

ExtJS

Ext.Object.isEmpty({}); // true

AngularJS (version 1)

angular.equals({}, {}); // true

Ramda

R.isEmpty({}); // true

How to check if object is empty in javascript for all levels in object

Here is the way to do what using recursion

const x = {  a:"",  b:[],  c:{    x:[]  },  d:{    x:{      y:{        z:''      }    }  }};function checkEmpty(obj){    for(let key in obj){    //if the value is 'object'    if(obj[key] instanceof Object === true){      if(checkEmpty(obj[key]) === false) return false;    }    //if value is string/number    else{      //if array or string have length is not 0.      if(obj[key].length !== 0) return false;    }  }  return true;}console.log(checkEmpty(x))x.d.x.y.z = 0;console.log(checkEmpty(x));

How to determine if a variable is an empty object, empty array or empty string?

Simply use Object.keys()

if (Object.keys(something).length) console.log("Not empty");

This works for all of strings, arrays, and of course, objects.

You can check the Object.keys documentation for more details, specifically, the examples section and the non-object coercion section, which state:

// simple array const arr = ['a', 'b', 'c'];
console.log(Object.keys(arr)); // console: ['0', '1', '2']

// array-like object const obj = { 0: 'a', 1: 'b', 2: 'c' };
console.log(Object.keys(obj)); // console: ['0', '1', '2']

and

In ES5, if the argument to this method is not an object (a
primitive), then it will cause a TypeError.

From ES2015 onwards, a non-object argument will be coerced to an
object.

// In ES5 Object.keys('foo');  // TypeError: "foo" is not an object

// In ES2015+ Object.keys('foo');  // ["0", "1", "2"]

javascript - check if object is empty

You were testing sellers which is not empty because it contains mergedSellerArray. You need to test sellers.mergedSellerArray

let sellers = {  "mergedSellerArray": {}};if (Object.keys(sellers.mergedSellerArray).length === 0 && sellers.mergedSellerArray.constructor === Object) {  console.log("sellers is empty!");} else {  console.log("sellers is not empty !");}

Check if Object is Empty in ES6

You can do this way

const checkIfVerifiedExists = (user) => {
    if (user && user.verified && Object.keys(user.verified).length) {
        return true;
    }
    return false;
};

console.log(checkIfVerifiedExists(null));
console.log(checkIfVerifiedExists({something: "a"}));
console.log(checkIfVerifiedExists({verified: null}));
console.log(checkIfVerifiedExists({verified: ""}));
console.log(checkIfVerifiedExists({verified: "a"}));
console.log(checkIfVerifiedExists({verified: "a", something: "b"}));

Checking if a state object is empty

Given that this.state.errors is an object you can do this,

//when this.state.errors object is empty 
if (Object.keys(this.state.errors).length == 0) {
  this.props.updateUser(user);
  this.props.navigation.goBack();
}

Object.keys will return an array or all the keys from the object this.state.errors. Then you can check the length of that array to determine if it is an empty object or not.

Check object empty

You can't do it directly, you should provide your own way to check this. Eg.

class MyClass {
  Object attr1, attr2, attr3;

  public boolean isValid() {
    return attr1 != null && attr2 != null && attr3 != null;
  }
}

Or make all fields final and initialize them in constructors so that you can be sure that everything is initialized.

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