type of an object

Posted on Fri 10th, May 2019

• #1

JumJum

How do I detect type of an object ?
For example var x = new SPI()
X returns SPI: { }, so in web IDE(only in web IDE) I see its an SPI object
typeof x returns ="object"
Is there any JS command, something like objectType, which returns "SPI"

• #2

AkosLukacs

If you know what type you expect, you can use instanceOf. For example:

if (!(serialPort instanceof Serial)) {throw '"serialPort" parameter is not a serial port!'}
if (!(rxPin instanceof Pin)) {throw '"rx" parameter is not a Pin!';}

• #3

Gordon
As far as I know there's nothing built-in, since the name of the object isn't actually stored in the object itself in Espruino.

However if the class is something that's defined in the global scope, like SPI, then you can do:
```
>x = new SPI()
=SPI: {  }
>Object.keys(global).find(n=>global[n]==x.constructor)
="SPI"
```
But if you know what you're looking for, you're far better off going with @AkosLukacs's suggestion as it's far faster and neater!

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