List of the 20 Most Important TypeScript Interview Questions of 2023

At an interview for someone with TypeScript experience, it is common to be asked some questions related to the language. For example, one question may be regarding the object-oriented notations that TypeScript recognises. Another question may be about the key differences between TypeScript and JavaScript. Knowing the answers to these questions can help demonstrate a candidate’s knowledge of TypeScript and can be used to assess their understanding of the language.

Trying to find the solutions to these issues? Proceed with the text.

Explain what TypeScript is.

TypeScript is a computer language that is syntactically a strict superset of JavaScript, offering developers the ability to write large-scale applications, transpile the code to JavaScript, and opt for optional static typing. The utilisation of TypeScript allows developers to take advantage of the increased readability, scalability, and maintainability of their code.

TypeScript source code is stored in files with the file extension “.ts”. The TypeScript compiler can then be used to generate the corresponding JavaScript code. Any text editor can be used to create these files. The compiler must be installed on the platform in order to use the TypeScript code. To compile the code, the command “tsc .ts” can be used. For example: tsc myScript.ts

Welcome to Works! var message:string = “Welcome!”


Simple TypeScript-based job interview questions

  1. Exactly how can TypeScript help while making apps?

    Here are some of TypeScript’s advantages while creating apps:
    1. TypeScript is fast, simple to understand, and runs rapidly, and it can be executed by any JavaScript engine or browser.
    2. Both the syntax and the semantics of TypeScript are identical to those of JavaScript. This helps developers create front-end code more quickly.
    3. TypeScript also works well with pre-existing JavaScript libraries and frameworks.
    4. The Definition file (which ends in.d.ts) allows you to use preexisting JavaScript libraries like Jquery, D3.js, and more.
    5. TypeScript’s ES6 and ES7 features are compatible with JavaScript ES5 engines, so you can use it with tools like Node.js.
  2. Please explain why TypeScript has drawbacks.

    Some of TypeScript’s drawbacks include the following:
    1. TypeScript has a long compilation time because of its complex syntax.
    2. It’s not possible to create an abstract class with TypeScript.
    3. If you wish to execute a TypeScript program in the browser, you’ll need to compile the TypeScript code into JavaScript first.
    4. A library definition file is required before use any external library.
    5. The quality of the type definition files is poor.
  3. What Does TypeScript Consist Of?

    TypeScript is a programming language that consists of three major components. These components can be thought of as distinct layers, each with their own code snippets that can be utilised. The three components of TypeScript are: static type checking, class-based object-oriented programming, and a sophisticated type system. Static type checking is a process of verifying the accuracy of the data types used in code. Class-based object-oriented programming allows you to create classes and objects to better structure your code and make it easier to maintain. The sophisticated type system in TypeScript allows for more precise and efficient coding by allowing for type inference and type aliasing. Each of these components provides its own unique set of benefits for the developers using TypeScript.
    1. Language
    2. That Thing You Do With The TypeScript Compiler
    3. Language Support for TypeScript
  4. Describe how Arrays in TypeScript work and what characteristics they provide.

    Features unique to TypeScript’s Arrays include the following.
    1. You can’t modify an array. This operation indicates that once an array has been built, its size cannot be changed.
    2. To illustrate, an array’s elements are stored in individual memory blocks.
    3. The subscript or index of an array element is a unique numerical identifier.
    4. Before a programmer can use an array, it must be defined. This can be done by specifying the ‘var’ keyword. Once this has been done, the array can be used in the same way that a variable can.
    5. When data is added to an array, it is said to be “first initialised.”
  5. Where do I put a TypeScript variable declaration?

    In order to declare a value, it is necessary to utilise either the `let` or `const` declarations. Both of these declarations are required for the successful declaration of a variable. Furthermore, it is essential that the following conditions are met in order for the declaration to be valid:
    1. Only alphanumeric letters and integers may be used in variable names.
    2. Besides the underscore (_) and the dollar sign ($), spaces and other non-alphanumeric characters are not allowed in variable names.
    3. A variable name cannot begin with a number.

      Syntax example:
      the variable an is set to 10;
      using the f()
      Hello, Works! var message =;
      message back;
  6. What kinds of access modifiers does TypeScript allow?

    TypeScript accepts the next set of access modifiers:
    1. Modifier for Secure Access
    2. Alteration for Confidential Use Only
    3. A Modifier for Open Access
  7. When using Typescript, what exactly are loop statements?

    By utilising a loop statement, code may be repeatedly executed. TypeScript offers a broad range of looping options to meet various looping requirements, including but not limited to the ones listed below.
    1. Regarding the loop:
    2. As Long As The Iteration Is In The While Loop
    3. The Do…While Loop
  8. To what extent may static typing be defined?

    At compilation time, a compiler with static typing has the capability to recognise variables, arguments, and object members. By utilising static typing, it is possible to detect programming mistakes before they create serious issues.
  9. To what extent may TypeScript be utilised for backend development?

    Yes. TypeScript’s enhanced security is a great perk for Node.js backend apps.
  10. To determine whether a TypeScript variable is undefined or not, what approach will you take?

    If value is not null, undefined, empty, false, 0 or NaN, the if (value) function will return true.

Problems for a more in-depth interview in TypeScript

  1. How do you define “type assertion”?

    Type assertions in TypeScript are used to explicitly inform the compiler of the data type of a given value in order to ensure that the compiler does not perform any additional data restructuring or verification. This type of assertion does not have any effect on the performance of the code and is only used to provide the compiler with the necessary information. It is the responsibility of the programmer to perform any necessary checks prior to using the assertion.
  2. So, what exactly are recursive type aliases?

    The use of a type alias in a recursive manner has not been commonly feasible due to the requirement of each alias type acting as a direct substitute for the targets it aliases. This makes sense; however, the compiler usually declines to accept recursive aliases as they are not always possible.

    Although type aliases are not able to be recursive, interfaces can be, although with somewhat limited capability. This is achieved by taking the process of creating an alias for a type and breaking down its recursive components as interfaces.

    The example syntax is as follows:
    type ValueOrArrayT> = T | ArrayOfValueOrArrayT>;
    ArrayOfValueOrArrayT> interface inherits ArrayValueOrArrayT>>
  3. The question is how to routinely get files of type “declaration.”

    Change the value of the declaration compiler option in tsconfig.json to true.

    Example syntax may be something like this:
    For “compilerOptions,”

    This “statement” is true,
  4. In what ways may a function be overridden?

    Reuse the same function name just above the first function, this time without using brackets. Adjust the input and output types, as well as the number of parameters, to your needs.

    A good illustration would be as follows:
    string function add(string x, string y);
    The addition method add(x, y) returns a larger value if x > y.
    revert x + y;
  5. Describe TypeScript Modules

    TypeScript code may be modularized using modules. There are two main categories of module. Here are a few of them:
    1. Moduli Interni: Prior to the most recent version of TypeScript, classes, interfaces, and functions were typically grouped together into what was referred to as “internal modules” before being exported to another module. This type of organisational logic is now referred to as a “namespace” within the TypeScript environment.
    2. Add-Ons and adapters: Developers working with TypeScript may take use of external modules to define and load interdependencies between several external js scripts.
  6. Methods for making all interface properties optional.

    Using the partial mapped type, programmers may turn any interface property into a purely optional one.

    Example syntax may be something like this:
    interfacing Person
    String for name;
    quantitative representation of age;
    type PartialPerson = Partial Person>; / As in the following lines
    The PartialPerson interface
    string for name;
    When asked their age, they gave a number;
  7. In what contexts may decorators be used?

    Classes, properties, methods, and method arguments are all valid places to apply a decorator.

    A good illustration would be as follows:
    import Person

    @MyPropertyDecorator string; myProperty;
  8. The Record serves what purpose, exactly?

    The Record library enables programmers to build a programmable, typed map.

    A good illustration would be as follows:
    In other words: let Person = Recordstring, number> = ;
    People.Age = 20;
  9. If you want to use classes that aren’t included in a certain module, how do you do it?

    To utilise a class that isn’t part of a module, you must use the export keyword before the class name.

    A good illustration would be as follows:
    import Person
  10. To start, let’s define Distributive Conditional Types.

    The checked type parameter in conditional and distributive conditional type declarations is a basic type parameter. Upon instantiation, the distributive conditional types become evenly distributed across the various union types.

    Instances of T extends U? X: Y are resolved as (A extends U? X: Y) | (B extends U? X: Y) | (C extends U? X: Y).

To that end, how can you best begin to prepare for queries about TypeScript?

Before diving in, know that TypeScript is a top-notch front-end web development tool because to the robust JavaScript support it offers.

As a result, it is anticipated that the interview questions will primarily focus on topics related to front-end development, such as HTML, CSS, frameworks, responsive design, version control, browser developer tools, web performance, user interface, and more. In addition, the interview may delve into the key aspects of TypeScript, including classes, components, arrays, functions, modules, interfaces, and generic and static typing.

In order to gain a greater understanding of the topics discussed, it is recommended that learners take the time to explore and practice the ideas and concepts presented. Furthermore, the suggested questions can be used as a helpful review guide. For those looking to further their knowledge, there are a number of free online coding environments that can provide an opportunity to gain practical experience and discover how these concepts can be applied in the real world.

If you are searching for an opportunity to secure a remunerative job in the United States, Works may be the answer for you. Works offers long-term, high-paying software engineering positions that can be performed remotely.


  1. Which object-oriented notations does TS recognise?

    The subsequent object-oriented notations are recognised by TypeScript:
    1. Modules
    2. Classes
    3. Interfaces
    4. Inheritance
    5. Data Formats
    6. Participant Roles
  2. When comparing JavaScript to TypeScript, what are the key differences?

    TypeScript is an object-oriented programming language that was specifically designed as an alternative to the existing online programming language of JavaScript. Whereas JavaScript is utilised for creating dynamic web pages, TypeScript is an open-source language that is particularly useful for developing complex online applications.

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