How do I output the value of an object property via dot?

Here is this code displays an error:
const example = { 1991: 1 }

But this displays the value for the key "user" without errors:
const example = { user: 1 }

Why the first example does not display the value of the key "1991"?
April 7th 20 at 10:42
2 answers
April 7th 20 at 10:44
example[1991], to go through point the name property must start with a letter
Thanks, did not know that there is such a limitation. - Erica.Bode50 commented on April 7th 20 at 10:47
April 7th 20 at 10:46
Worth a read, for example here:

Restrictions on property names

We can only use strings and symbols as keys of properties. All other data types will be automatically converted to a string.

For example, if you use the key number 0, it will become the string "0"

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