Class type check in TypeScript

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4.19.4 The instanceof operator

The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, and the right operand to be of type Any or a subtype of the ‘Function’ interface type. The result is always of the Boolean primitive type.

So you could use

mySprite instanceof Sprite;

Note that this operator is also in ActionScript but it shouldn’t be used there anymore:

The is operator, which is new for ActionScript 3.0, allows you to test whether a variable or expression is a member of a given data type. In previous versions of ActionScript, the instanceof operator provided this functionality, but in ActionScript 3.0 the instanceof operator should not be used to test for data type membership. The is operator should be used instead of the instanceof operator for manual type checking, because the expression x instanceof y merely checks the prototype chain of x for the existence of y (and in ActionScript 3.0, the prototype chain does not provide a complete picture of the inheritance hierarchy).

TypeScript’s instanceof shares the same problems. As it is a language which is still in its development I recommend you to state a proposal of such facility.

See also:

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