This declaration creates a constant whose scope can be either global or local to the block in which it is declared. Global constants do not become properties of the
window object, unlike
An initializer for a constant is required. You must specify its value in the same declaration. (This makes sense, given that it can't be changed later.)
const creates a read-only reference to a value. It does not mean the value it holds is immutable—just that the variable identifier cannot be reassigned. For instance, in the case where the content is an object, this means the object's contents (e.g., its properties) can be altered.
All the considerations about the temporal dead zone apply to both
A constant cannot share its name with a function or a variable in the same scope.
const begins declarations, not statements. That means you cannot use a lone
const declaration as the body of a block (which makes sense, since there's no way to access the variable).