TypeScript Language Specification v1.5

f < T1, T2, ... > ( p1, p2, ... ) : R ;
f < U1, U2, ... > ( q1, q2, ... ) : S ;
...
is equivalent to
f : {
< T1, T2, ... > ( p1, p2, ... ) : R ;
< U1, U2, ... > ( q1, q2, ... ) : S ;
...
} ;
In the following example of an object type
{
}
func1(x: number): number;
func2: (x: number) => number;
func3: { (x: number): number };
// Method signature
// Function type literal
// Object type literal
the properties 'func1', 'func2', and 'func3' are all of the same type, namely an object type with a single call
signature taking a number and returning a number. Likewise, in the object type
{
}
func4(x: number): number;
func4(s: string): string;
func5: {
(x: number): number;
(s: string): string;
};
the properties 'func4' and 'func5' are of the same type, namely an object type with two call signatures
taking and returning number and string respectively.
3.9 Type Aliases
A type alias declaration introduces a type alias in the containing module.
TypeAliasDeclaration:
type Identifier = Type ;
A type alias serves as an alias for the type specified in the type alias declaration. Unlike an interface
declaration, which always introduces a named object type, a type alias declaration can introduce a name
for any kind of type, including primitive types and union types.
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