function accepts one argument either object or null

Question

I have a scenario where function only gets one argument which could be either object or null. As both object and null has type of object. How can I use if statement on them to differentiate? If I use typeof then both object and null will return object.

UPDATE

function func (par) {
    if (par === null) {
        console.log(null);
    }

    if (typeof par === "object") {
        console.log(object);
    }
}

func({key1: 'val1', key2: 'val2'});
func(null);

I don't understand the problem. You're checking for null value and then you're checking the type to see if it's an object. Isn't that what you intended to do? — CatDadCode, Feb 20 '14 at 20:39
null is not an object, it is a primitive value. check this page : [link] http://stackoverflow.com/questions/801032/why-is-null-an-object-and-whats-the-difference-between-null-and-undefined — vahid, Feb 20 '14 at 20:42
@AlexFord No because the second condition is true for both `object` and `null`. — Om3ga, Feb 20 '14 at 20:44

Rob M. · Accepted Answer · 2014-02-20T20:46:12.557

6

You can just check if the argument is null:

UPDATED (per change in problem definition)

if(arg === null)

function func (par) {
    if (par === null) {
        console.log(null);
    } else if(typeof par === "object") {
        console.log(par);
    } else {
        console.log("Unexpected parameter");
    }
}

func({width: '1px', color: 'orange'});
func(null);

edited Feb 20 '14 at 20:46

answered Feb 20 '14 at 20:32

Rob M.

35,491
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You've added `object`, not sure where that variable came from – Rob M. Feb 20 '14 at 20:39
The problem with this is that the second if condition will be true for both `object` par and `null` par. That is what I don't want. – Om3ga Feb 20 '14 at 20:42
Then use `else` instead of 2 `if`s, updating my example – Rob M. Feb 20 '14 at 20:44
Is there a better solution rather than using several if else if. – Om3ga Feb 20 '14 at 20:48
1

Better solution to what? You asked how to check if something was null. Really, you don't need an else if, just an else. – Rob M. Feb 20 '14 at 20:55

score 1 · Answer 2 · answered Feb 20 '14 at 20:46

1

If you need to know if it is null OR of type object then simply make the second if an else if.

function func (par) {
    if (par === null) {
        console.log(null);
    } else if (typeof par === "object") {
        console.log(object);
    }
}

func({key1: 'val1', key2: 'val2'});
func(null);

http://codepen.io/Chevex/pen/GbKeg

answered Feb 20 '14 at 20:46

CatDadCode

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Is there any other solution? I mean better one. – Om3ga Feb 20 '14 at 20:47
lol, what does that even mean? Better how? If you *have* to know that `par` is an object then there is no better way to check that. If you don't *have* to know what the type is after you know it's not `null` then you can just use a simple `else` instead of `else if`. Other than that I don't know what else to tell you. – CatDadCode Feb 20 '14 at 21:02

function accepts one argument either object or null

2 Answers2