Deleting a non-string in js object

Question

Let's say I have the following object:

const a = {a: 1, 0: 2};
delete a.a; // this works
delete a.0; // this errors (I suppose expecting a['0'] and not a[0])

Does the method deletion form of obj.key only allow deletion of a string key? And if it's a non-string type, is the only way of doing deletion via the key lookup method of obj[key] ?

VisioN · Accepted Answer · 2021-10-08 21:50:32Z

1

According to MDN:

In the object.property syntax, the property must be a valid JavaScript identifier.

... where ...

... identifiers are case-sensitive and can contain Unicode letters, $, _, and digits (0-9), but may not start with a digit.

So, answering your question, property with name 0 can be only accessed with key notation.

edited Oct 8, 2021 at 21:50

answered Oct 8, 2021 at 21:49

VisioN

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5 Comments

David542 Over a year ago

I see. So in that case, is the most common way to delete a non-string object using the lookup syntax? Are there other ways as well, or that's the only way?

VisioN Over a year ago

Only using key notation, i.e. delete obj[non-identifier].

dave Over a year ago

And to clarify, except in the case of symbols, all keys will be strings. Just, in this case, it's being coerced from a number when you declare it

David542 Over a year ago

@dave I see, so even doing {0: 2} will give me {'0': 2}? I just cannot use property notation because a leading 0 is not allowed as a legal identifier?

dave Over a year ago

@David542 exactly - if you do Object.keys({0: 2}) you'll get ["0"]. It's only because when using dot notation the property must be a valid JavaScript identifier

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