Type assertion in TypeScript

TypeScript Advance Types: Exercise-7 with Solution

Write a TypeScript program that declares a variable as type any and uses a type assertion to explicitly cast it to type string.

Sample Solution:

TypeScript Code:

// Declare a variable 'anyValue' as type 'any'
let anyValue: any = "This is type 'any'";

// Use a type assertion to cast 'anyValue' to type 'string'
let stringValue: string = anyValue as string;

// Print the value and type of 'stringValue'
console.log("stringValue:", stringValue);
console.log("Type of stringValue:", typeof stringValue);

Explanations:

In the exercise above,

• First, declare a variable 'anyValue' as type "any". When a variable is of type "any", it can hold values of any type without type checking.
• Assign a string value to 'anyValue'.
• Use a type assertion to explicitly cast anyValue to type string.
• Declare a variable stringValue as type 'string' and assign the casted value to it.
• Finally, we print the value and the type of stringValue to the console.

Output:

"stringValue:"
"This is type 'any'"
"Type of stringValue:"
"string"

TypeScript Editor:

See the Pen TypeScript by w3resource (@w3resource) on CodePen.

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