Code below throws Spread types may only be created from object types:
const bool = true
console.log({ ...(bool || { foo: 'bar' }) })
While the following works fine, what caused the above error and how to suppress it?
const bool = true
console.log({ ...(bool && { foo: 'bar' }) })
When you do the ||, it evaluates the item on the left and tries to spread it. But it cannot spread a boolean variable, it can only spread an object.
When you do the &&, the expression in parens returns the { foo: 'bar' } object, which is spreadable.
To play with this, try:
console.log(true && 'hi') // "hi"
console.log(true || 'hi') // true
The first one translate like this
If bool is true or the object... In that case it's trying to spread the bool but seeing that bool is a Boolean not an object... You get the error
The second translate like this
If bool is true, then spread this object... The ampersand in that case is doing a check, making sure bool is true before spreading the object... This is equivalent to writing an if statement...
if (bool) console.log({ ...{ foo: 'bar' } })