This is useful when you are getting dynamic values and when you want to pass through compile-time checks. 'Void' is somewhat opposite of 'any'. Actually it is useful when your function is not returning anything. 'Void' type is a sub-type of the 'Any' type and a super-type of the 'Null' and 'Undefined' types.
var variableName: variableType = value;
The TypeScript types are defined in a file called lib.d.ts a.k.a Library Definition Files. One more thing to note here is that all types in TypeScript are subtypes of a single type called 'Any' Type whereas 'Null' type is a sub-type of all types, except the 'Undefined' type. This means that null is considered a valid value for all the primitive types.
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