TypeScript Any Type

Any type is the base type for all other types in TypeScript. Any type can represent any JavaScript value with no constraints. The TypeScript compiler does not perform type checking on the Any type. The Any variable can hold anything like primitives, objects, arrays, functions, errors, symbols, etc.

Declaring Any Type

The typescript creates a variable as Any under the following circumstances

  1. If you do not declare the type and typescript does not infer the type from its initialization or from its usage (inferred typing).
  2. You explicitly declare the type as Any (explicit typing)

For Example, Typescript creates the variables  var1 and var2 as of type Any.

No Type Checking

The Typescript compiler does not make type checking on the variable of type Any.  When you define a variable as Any, you are basically opting out of type checking. For Example, the following code compiles & runs without any issue. Although we assign string, object, and number to the anyvar variable.

The following code also compiles although the toFixed method does not exist on object. But when you run the code you will get the following error. TypeError: anyVar.toFixed is not a function

When to use Any

You should avoid using Any as you will lose the benefit of the type checking. The type errors occur only at runtime and that is against one of the main reasons why use TypeScript.

But there are many scenarios where you may not know the type of the variable. The following are two such scenarios, where using Any makes sense.

When working with third party libraries

You can use Any when you do not know the data type of the variable. This may be the case when you work with the third-party libraries and does not want the compiler to throw errors

Existing JavaScript

When you port your existing JavaScript code. You can make use of the any type until you migrate the program to typescript.

References

  1. Basic Types

Leave a Comment

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top