对于给出 TypeError 的空对象：无法将 undefined 或 null 转换为对象

Question

Well, I know this is would be a very common question but I tried to find the solution but no luck yet. So here is the problem statement :

Due to some condition, my object is having no values and it is empty {} and when I try to check the length of this object using Object.keys(ambassador).length OR Object.entries(ambassador).length it is giving me the error

TypeError: Cannot convert undefined or null to object.

Code sample:

const ambassador = Array.isArray(ambassadors) 
        ? ambassadors.find((item) => {
                return item.affiliate_id === affiliate.tracking_id;
            })
        : {};

console.log(ambassador == null); //false
console.log(typeof(ambassador)); // Object
console.log(Object.keys(ambassador).length > 0 ); //TypeError: Cannot convert undefined or null to object.

Answer 1

So, I got solution from the comment of Kireeti Ganisetti, He suggested to use LOADASH and it worked :)

To check if the object is empty in Javascript - React :

import _ from 'lodash';
_.isEmpty(ambassador)

Answer 2

As mdn says :

The value null represents the intentional absence of any object value. It is one of JavaScript's primitive values and is treated as falsy for boolean operations

Try to check your object whether it is not null before reading keys:

let ambassador = null;
console.log(ambassador == null); //false
console.log(typeof(ambassador)); // Object
if (ambassador)
    console.log(Object.keys(ambassador).length > 0 );

An example:

 let ambassador = null; console.log(ambassador == null); //false console.log(typeof(ambassador)); // Object if (ambassador) console.log(Object.keys(ambassador).length > 0 );

UPDATE:

If let ambassador = {}; then abmassador is truthy so you can check keys of the object:

let ambassador = {};
console.log(ambassador == null); //false
console.log(typeof(ambassador)); // Object
if (ambassador)
    console.log(`ambassador`, Object.keys(ambassador).length > 0 );

As mdn says :

In JavaScript, a truthy value is a value that is considered true when encountered in a Boolean context. All values are truthy unless they are defined as falsy (ie, except for false, 0, 0n, "", null, undefined, and NaN).

Examples of truthy values in JavaScript (which will be coerced to true in boolean contexts, and thus execute the if block):

if (true)
if ({})
if ([])
if (42)
if ("0")