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How to useType Guards in Typescript

Approach 2: Using instanceof Operator

You can create custom type guards using functions that narrow down the type of a variable based on certain conditions.

Example: In this example, we are using Type Guards to get the type of a variable.

Javascript




function isString(value: any): void {
    if (typeof value === "string") {
        console.log("It's a string!");
    }
    else{
        console.log(`Passed value is
                     of ${typeof age}
                     type.`)
    }
}
 
let greet: any = "Hello, TypeScript!";
const age: any = 20;
 
isString(greet);
isString(age);
 






                        









													
													
												

												
												

													
													
Output:

													
													
												

												
												

													
													
It's a string!
Passed value is of number type.

													
													
												

												
												

													
													

													
													
												

												
												

													
													

													
													
												

												
												

													
													

													
													
												

												
											

											
											

												
How to Get a Variable Type in TypeScript ?

												
												

													
													
To get a variable type in TypeScript, we have different approaches. In this article, we are going to learn how to get a variable type in Typescript.

													
													
												

												
												

													
													
Below are the approaches used to get a variable type in TypeScript:

													
													
												

												
												

													
													


Table of Content


    

  • Using typeof Operator
    • 

  • Using instanceof Operator
    • 

  • Using Type Guards
    • 




													
													
												

												
											

										


										
										

											
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														Approach 1: Using typeof Operator

													

														You can use the typeof operator to get the type of a variable at runtime. It returns a string representing the type of the operated variable....
													

												
											

											
											

												
													

														Approach 2: Using instanceof Operator

													

														...
													

												
											

											
											

												
													

														Approach 3: Using Type Guards

													

														The instanceof operator checks if an object is an instance of a particular class or type. It can be used to check the type of an object....
													

												
											

											
										


									

									

										
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												Approach 2: Using instanceof Operator