JavaScript API Response - if clause for 'null' response

Question

Can someone assist, please, in following case:

Have a .json response with person's data where, that person can or can not be assigned to some project.

Below is part of response where person is not assigned to project:

"contactPerson": {
      "id": "someUUID",
      "firstName": "string",
      "lastName": "string",
      "email": "string",
      "title": "string"
    },
    "project": null

Response where person is assigned to a project:

"contactPerson": {
      "id": "someUUID",
      "firstName": "string",
      "lastName": "string",
      "email": "string",
      "title": "string"
    },
    "project": {
      "id": "projectUUID",
      "name": "This is a project name ",
      "fullName": "This is a full project name with over 55 chars",
}

Tried with simple if clause, but without success.

if (typeOf(response.body[i].project.id !== null) {
 //assert elements in project array
} else {
//assert is 'null
}

Always got followin error:

Cannot read properties of null (reading 'id')

Does anyone have the idea how to solve it? Assert if there is assigned project or not.

Thank you in advance

Answer 1

In fact, response.body[i].project.id will be undefined since response.body[i].project is null.

It will actually throw an error;

TypeError: Cannot read properties of null (reading 'id')

As mentioned in comments, simply checking response.body[i].project is enough.

Checking with typeof on response.body[i].project will actually return object.

So either check;

if(response.body[i].project)

This works since null is falsy value, and it is equal to doing;

if(response.body[i].project == null)

To actually check if null;

if(Object.is(response.body[i].project, null))

Or

if(response.body[i].project === null)

const response = {
  "contactPerson": {
      "id": "someUUID",
      "firstName": "string",
      "lastName": "string",
      "email": "string",
      "title": "string"
    },
    "project": null
};

console.log(response.project); // null

console.log(typeof(response.project)); // object

console.log(response.project == null); // true

console.log(response.project === null); // true

console.log(Object.is(response.project, null)); // true