CODEWITHSUNDEEP
javascripttypescriptdebugging
Shakir Aqeel
Shakir Aqeel

Reputation: 352

Why any type is allowed in typescript? where it makes difficult to catch error at compile time

Why any type is allowed in typescript. It may generate bugs at runtime, and type any makes it difficult to detect bugs at compile-time. Example:

const someValue: string = "Some string";
someValue.toExponential();

When I define its type string it shows a compilation error. Because toExponential() is not a function for string type data. But when I change its type to any.

const someValue: any = "string";
someValue.toExponential();

It does not show any compile-time error and generate an error at run-time. So, what is the exact use of type any? and how to avoid run-time error while using type any.

Upvotes: 1

Views: 1266

Answers (2)

Ramesh
Ramesh

Reputation: 13266

One of the use of any type is that, when migrating a large codebase from js to ts, any can be used as a stopgap arrangement.

Upvotes: 1

Shakir Aqeel
Shakir Aqeel

Reputation: 352

You should avoid the use of type any in typescript because it can cause ambiguity in your code and may lead to run-time errors. Because any type means the type will be decided at runtime. Which type of data it contains same will be the type of the variable. Example:

let someVariable: any ;
somVariable = 1000;

somVariable's type will be read as a number at run-time.

somVariable = "string";

if somVariable contains a string the type will be read as a string at run-time.

The type mismatch error will be generated at run-time if there is a mismatch because the type is decided at run-time of any.

But sometimes it is easy to use the type Any. Suppose, you are getting someValue from someFunction(). You don't know the return type of someFunction(), and you don't have to perform type-bound operations on the data. You may use type any.

const someValue: any = someFunction();
console.log(someValue);

You have to be careful using type any to avoid run-time errors.

Upvotes: 2

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