I don't understand about spread syntax inside objects.
console.log(...false) // TypeError not iterable
console.log(...1) // TypeError not iterable
console.log(...null) // TypeError not iterable
console.log(...undefined) // TypeError not iterable
I understand above codes that occurs error because of none-iterator.
But these codes are working well.
console.log({...false}) // {}
console.log({...1}) // {}
console.log({...null}) // {}
console.log({...undefined}) // {}
Please let me know why the above codes are working.
The object spread is quite different. It maps to Object.assign() internally.
So const a = {...1} is same as const a = Object.assign({}, 1)
Here Object.assign({},1) has treated 1 as object not as number. Therefore, you did not get any exception thrown.
Additionally if you have tried same thing for arrays [...1] it should have thrown error, since it does not treats 1 as object and you get the same behavior as ..1.
To summarize:
console.log({...false}) => console.log(Object.assign({}, false))
console.log({...1}) => console.log(Object.assign({}, 1))
console.log({...null}) => console.log(Object.assign({}, null))
console.log({...undefined}) => console.log(Object.assign({}, undefined))