Why is typeof() giving me strange results?

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Good afternoon JavaScript types. I have a simple query perhaps you could explain to my thick brain.

console.log(typeof(100));

outputs 'number'. Well of course it does.

console.log(typeof(100).toString());

outputs 'string'. Now I'm confused, but if I do this:

console.log((typeof(100)).toString());

I get back to 'number' again. These last two things are identical according to my C# eyes, so there's clearly something probably quite simple I'm missing here. Why does the second example print out 'string'?

What I have tried:

I object to being forced into telling what I've tried.

Posted 2-Apr-20 2:26am

Rob Philpott

Updated 2-Apr-20 2:49am

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3 solutions

Solution 1

Right, answered my own question. The second one is the equivalent of

console.log(typeof ((100).toString()))

Because in JavaScript the brackets appear optional when using typeof. I think I need a bucket to be sick in.

Posted 2-Apr-20 2:45am

Rob Philpott

Comments

Richard Deeming 2-Apr-20 8:46am

Yes - typeof is an operator, not a function. :)
typeof - JavaScript | MDN[^]

Rob Philpott 2-Apr-20 8:54am

Perhaps it's just a rite or passage for those arriving at JavaScript from proper languages, but its really making me feel quite ill.

Richard Deeming 2-Apr-20 8:56am

Wait until you start trying to work out what this points to. :)

this - JavaScript | MDN[^]

OriginalGriff 2-Apr-20 9:06am

Welcome to Hell - I'd run for the doors now if I was you ...

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MadMyche · Accepted Answer · 2020-04-02T02:45:00

I understand it is confusing; the easy explanation is that is an order of operations, and the type-conversion is done before the type-evaluation.

I spaced it out to show you how this is being evaluated in your last 2 lines of codes

C#

console.log( typeof         (100).toString()  );
console.log( (typeof(100))  .toString()       );

Estys · Accepted Answer · 2020-04-02T02:51:00

Solution 3

typeof is not a function, it's an operator.

try :
typeof 100
typeof 100.toString() // error
typeof (100).toString()

Posted 2-Apr-20 2:51am

Estys