TypeScript Language Specification v1.5

var a;
// any
var b: number;
// number
var c = 1;
// number
var d = { x: 1, y: "hello" }; // { x: number; y: string; }
var e: any = "test";
// any
The following is permitted because all declarations of the single variable 'x' associate the same type
(Number) with 'x'.
var x = 1;
var x: number;
if (x == 1) {
var x = 2;
}
In the following example, all five variables are of the same type, '{ x: number; y: number; }'.
interface Point { x: number; y: number; }
var a = { x: 0, y: undefined };
var b: Point = { x: 0, y: undefined };
var c = { x: 0, y: undefined };
var d: { x: number; y: number; } = { x: 0, y: undefined };
var e = { x: 0, y: undefined };
5.1.2 Destructuring Variable Declarations
A destructuring variable declaration introduces zero or more named variables and initializes them with
values extracted from properties of an object or elements of an array.
DestructuringVariableDeclaration:
BindingPattern TypeAnnotation opt Initialiser
BindingPattern:
ObjectBindingPattern
ArrayBindingPattern
ObjectBindingPattern:
{ }
{ BindingPropertyList , opt }
BindingPropertyList:
BindingProperty
BindingPropertyList , BindingProperty
88