TypeScript Developer Course in 2025 – Beginner to Expert

Set up your TypeScript development environment with a code editor. Install TypeScript, write plain JavaScript in TypeScript, and understand the compilation stage and project configurations.

Set up your TypeScript development environment by installing Node.js, choosing the right installer, using VS Code, and globally installing TypeScript with npm, then verify with tsc -v (4.8.4).

See how JavaScript runs inside TypeScript, address type safety limits, then compile TypeScript to JavaScript with tsc, link to HTML, and enable prettier formatting on save.

Learn how TypeScript infers variable types from values. See how explicit annotations enforce numbers and reveal type errors like string not assignable to number in static typing.

Learn how the TypeScript compiler converts TypeScript to JavaScript. Configure tsconfig to target 2016, set rootDir, outDir (dist), remove comments, enable noEmitOnError, and strict typing.

Explore the fundamentals of type annotations in TypeScript, prioritizing type safety as you learn numbers, booleans, strings, and built-in types such as any and arrays.

Learn TypeScript primitive types: number, string, and boolean, through type annotations and a hands-on workflow from tsconfig setup to live compilation, dist output, and browser console results.

Explore the any type in TypeScript, representing any value and when it might be used. Avoid any, as it erodes type checking, shown by the password example.

Explore how the TypeScript array type enforces a single data type and how to create arrays of numbers, strings, and mixed types using union types and nested arrays.

Learn how TypeScript tuples form fixed-length arrays with strict type annotations, and how JavaScript compilation preserves their structure, including string and number order and type inference.

Explore TypeScript enums, defining constants with numeric, string, and heterogeneous values. Declare enums with enum, apply Pascal case, and access values via dot, shown by roll numbers and student details.

Explore basic implementations of conditionals and loops in TypeScript, including if statements, for loops, for-of loops, and for-in loops, to practice modern JavaScript concepts.

Discover how TypeScript adopts JavaScript conditionals with type-annotated numbers and if statements, including else ifs and the ternary operator for clearer logic.

Learn how for loops work in TypeScript, annotate numbers, iterate over arrays using length, and log indices and items with type inference matching JavaScript behavior.

Discover for-of loops in TypeScript and JavaScript, a newer, simpler way to iterate over arrays as iterables, with optional index via entries and array destructuring for clarity.

Explore for...in and for...of loops to get indices and items from arrays or tuples, convert string indices to numbers with unary plus, and print data points via template literals.

Explore coding challenges with solutions shown on the whiteboard and downloadable resource files. Learn to navigate concept-based challenges from basic types, using challenge and solution files to practice.

Declare a variable with type number as part of the basic types challenge, add a type annotation, and assign it a value such as 19 using let.

Solve the second challenge by creating a string variable with a type annotation. Concatenate two words with the + operator using let and a camelCase identifier.

Demonstrate a type error by assigning a number to a string in a basic types challenge, showing how type annotations in TypeScript produce a compilation error and guide debugging.

Explore declaring a boolean variable with TypeScript using let, annotate it as boolean, and apply the or operator to compare values while guarding type safety.

Simulate a type error in TypeScript by assigning a number to a boolean, annotating the variable, and observing the error 'type number is not assignable to type boolean'.

Declare a string, an arbitrary string, with let language, type annotate it as string, and use the dot operator to access its length, demonstrating basic type checking and string properties.

Discover how TypeScript inference infers types from values and why explicit type annotations boost readability and prevent runtime errors.

Solve TypeScript inference challenges by showing how assigning a string without a type annotation yields a string, and why explicit annotation to string matters.

Explore inference in TypeScript by assigning a boolean false to an untyped variable with let, showing how TypeScript infers the boolean type and guides beginners through the third challenge.

Learn how to create a number array in TypeScript by using proper type annotations and the array syntax with square brackets, ensuring the array holds only numbers.

Explore accessing the second indexed item in a zero-based array using bracket notation and console.log, reinforcing how JavaScript arrays map indices to their values.

Create an array of two boolean values in TypeScript, using true and false, and demonstrate how non-boolean values produce a type or compilation error.

Explore challenge 4: creating an unannotated TypeScript array with a number and a string, observe the inferred string | number union, and review array syntax and type annotation.

Explore annotating a TypeScript array with number, boolean, and string using union types and array syntax, creating a mixed array and assigning values like books, 50, and false.

Explore arrays in TypeScript by creating a number array and annotating it to number. Assign a string to trigger the simulated type error, type string not assignable to number.

Create a string type tuple in TypeScript by declaring a let variable, annotating it as a string, and using tuple syntax that resembles an array.

Solve the second tuples challenge by creating a number type tuple with precise type annotation and correct tuple syntax, reinforcing that a number type tuple cannot store other data types.

Create a string and number type tuple, annotate its types, access the second item by index 1, and log it to the console.

Create an enum of product names and display it on the console using console.log; learn enum basics and the pascal casing naming convention for types.

Create an enum of product IDs for laptop, mouse, and keyboard, start the IDs at 1 for mouse, and log the assigned IDs to the console.

Create and use an enum to represent a favorite product, reference product names and IDs, and display the result in the console using template literals.

Learn to implement a conditional that prints congrats when age is 21 or older, using a number-typed age variable and a console.log statement in TypeScript.

Loop through search history array with for-of and map methods to detect HTML or CSS, and display the message 'would you like to learn how to create websites for free?'

Explore how to write and type functions in TypeScript, including parameters and return annotations, and compare function declarations, function expressions, and error functions.

Explore TypeScript function declarations, annotate parameter and return types, and implement a holiday sales calculator using product, price, tax, and discount to compute net profit.

Convert function declarations to function expressions in TypeScript, and configure tsconfig to warn on unused parameters during the tsc -w watch.

Convert a function to an arrow function in TypeScript. Learn how to use no unused locals to catch unused variables and improve code quality.

Master TypeScript functions by learning how to create, type annotate parameters and return values, and maintain a type-checked system through coding challenges solved on a whiteboard.

Implement a type annotated TypeScript function that multiplies two numbers, annotate parameters and return type, and demonstrate a type error when passing a string.

Explore simulating type errors in TypeScript by building an emailList function that returns a string while accepting an arbitrary return type, using an example to illustrate type checking.

Explore TypeScript by implementing an arrow function that returns the addition of a number and a boolean, observe the implicit return with braces removed, and understand the resulting type error.

Learn to implement a pluralized function in TypeScript by accepting a string and returning the string with an s appended, demonstrated using a function expression in a practical challenge.

Explore two TypeScript function approaches to increment or decrement a number based on a boolean, including a long if-statement version and a compact ternary solution.

Create a TypeScript function that accepts a number array and returns the same array, enforcing numbers and throwing a type error when a non-number like a string is passed.

Master TypeScript basic types, including void, null and undefined handling, type aliases, typecasting, union and intersection types, to build a solid foundation for future sections.

Explore the void type in TypeScript, learn how functions that return nothing are inferred or explicitly annotated as void, and understand how undefined signals the lack of a return value.

Explore the never type in TypeScript, where a function that never completes makes code unreachable, with an infinite loop example and config options about unreachable code.

Explore how TypeScript handles null and undefined, enforce strict null checks, and implement a discount function that returns 25% on holidays and 15% otherwise, while handling null and undefined safely.

Learn how TypeScript enforces nullability with the undefined type, introduces union types like undefined | number, and explains why null is not assignable to number or undefined.

Learn how type aliases create named, constrained types in TypeScript, using literal and union types to restrict values (like four discounts) and define object shapes for type safety.

Explore recursive types in TypeScript by using self-referential type aliases to build nested arrays, and learn that these types compile away at runtime and never appear in JavaScript.

Learn how to use TypeScript type assertions to cast JSON data to an employee type (id, name, department) via old angle-bracket and newer parse generics, including stringify and local storage.

Explore how union types let variables and function parameters accept number or string, use type guards and narrowing to safely handle mixed inputs in TypeScript.

Learn how literal types in TypeScript lock values to exact literals—numbers, strings, booleans—and how unions constrain options like 25, 35, 45 or 0.15, 0.2, 0.25 and HTML, CSS, JavaScript, React.

Learn how intersection types in TypeScript combine product properties with discounts, seasonal sales, subscriptions, and shipping into a single blueprint, demonstrating an and-like composition and that types are compiled away.

Explore defining a function type in TypeScript by using a function signature with a string parameter and a string return type, and distinguish between signature and definition.

Explore optional parameters in TypeScript, using the ? syntax to mark them optional and observe compile-time errors for missing arguments. Learn how to prevent undefined values with default parameters.

Explore how default parameters in TypeScript provide fallback values when arguments are omitted, using a 10.99 default price and clarifying function signatures versus implementations.

Explore typing object shapes in TypeScript using inline annotations and a reusable product type alias. Learn to enforce the read only property and add optional fields like released.

Pass a literal object into a function and return its full name as a string, illustrating literal object types, type aliases, and structuring.

Tackle basic TypeScript types—union types, type aliases, literal types, function types, and object types—through challenges in part three of let's get you caring challenges, with a whiteboard explanation.

Explore union types by solving a TypeScript challenge: a function with a string or number return type, and a type-annotated variable demonstrating how compilation enforces type safety.

Explore union types in TypeScript, focusing on function invocation with type annotations and why assigning a string | number union to a number causes compile-time errors and affects type safety.

Explore union types in TypeScript with a challenge where a function returns a number and a variable holds number or string, showing that a number fits the union.

Explore type aliases by creating a PascalCase alias named BoolValues with the type keyword, assigning it to the boolean values true and false.

Explore type aliases in TypeScript as we trace a score alias of number and a string average score, showing how mismatched type annotations trigger compilation errors and reveal the solution.

Discover how a type alias score defined as number aligns with the average score and yields 11.5. Show how this type alias challenge solution demonstrates type compatibility.

Explore literal types in TypeScript and solve challenge 1 by distinguishing values from types, resolving the mismatch between string return types and mysterious type.

Explore literal types in TypeScript by enforcing a union of three strings, such as The Kite Runner and 1000 Splendid Suns, via a type alias and API key examples.

Explore TypeScript literal types with a practical challenge that enforces a book type of A, B, or C; it flags errors when encountering D or The Shining.

Explore literal types in TypeScript by distinguishing values from types, and learn why false can be a type, not a value, causing a compilation error when assigned to true.

Explore the first challenge solution for function types, showing a multiply function that takes a number, returns a number, and yields 121 when invoked with 11.

Explore function types in TypeScript and diagnose a return type mismatch that triggers type errors and compilation errors when a function returns a string instead of a number.

Explore creating aTypeScript function that accepts string, number, or boolean and returns a string. Use type annotations, convert inputs to strings, and store the function in a variable.

Learn to write a function that inverts a boolean value using the not operator, accepting a boolean and returning its opposite, flipping true to false and false to true.

Create a TypeScript function that takes a number and an operation ('add', 'subtract', or 'do something'), returning the adjusted number. Learn union types and literal types to enforce the behavior.

Explore function types in TypeScript through challenge six, illustrating how an untyped function has void type and cannot be assigned to a number, causing a type error.

Explore function types in TypeScript through the challenge seven solution. It shows a function with a price (number) and course (string) that returns a string and calls another function.

Define a TypeScript function type that takes no parameters and returns a string, using the type keyword and naming it someFunc. Observe the no-parameter function signature.

Define a type alias Employee with name, age, and job. Create an object matching that shape and show TypeScript enforces string and number properties.

Master object types in TypeScript by accessing a multi word property with bracket and dot notation to retrieve the nested published flag from metadata, yielding true.

Fix the error in a TypeScript object type by making the optional published status property, and understand how value types influence object shape when validating product objects.

Learn how the spread operator expands an online course object into a product object, merging name and price, then adds released: true for console logging in a TypeScript context.

Learn to define a product type with a holidaySales method in TypeScript, return a string, and print sale is on to the console.

Create a function that accepts a literal object with a string name property and returns that name. Use object destructuring to access the name directly.

Define a function named online that accepts a literal object with a boolean online property and returns that value. Demonstrate literal object types and the object structuring syntax in TypeScript.

Shows why assigning null to a variable typed as number | undefined produces a compilation error; null is not assignable to number or undefined.

See how assigning a boolean to a vague boolean | undefined causes a type error, while a conditional may return true or undefined depending on scope and type compatibility.

Explore nullability in TypeScript by solving third challenge: assign string or undefined and determine the result. The lecture clarifies that undefined is compatible with string | undefined, while null differs.

Resolve nullability logic by solving challenge four, showing how week two becomes true or undefined based on week one’s boolean or undefined state, using a ternary evaluation.

Explore nullability and type narrowing in TypeScript by building a function that accepts a string or undefined and returns a number or undefined, using parseInt and isNaN to validate input.

Explore generics in TypeScript to enable flexible, type-safe code reuse with generic arrays, generic functions, and object types.

Explore how to create generic arrays with type parameters using angle brackets, including numbers, strings, booleans, nested arrays, and mixed onion-type arrays.

Explore how generic functions in TypeScript enable a single function to work with any data type, using a get array item example with type parameters, inference, and safety.

Explore generic object types in TypeScript by turning type aliases into flexible, type-safe shapes with generics, type parameters, and type arguments, illustrated by book cover and product examples.

TypeScript infers generic function types at call time, letting a generic function handle arrays and return a number like array length, with safe type inference even without explicit type arguments.

Explore generic function types in TypeScript by extracting a function signature into a type alias, using a type parameter, and showing when a function is generic or specialized.

Explore TypeScript generic sets, create with new Set, and prevent duplicates in iterable collections. Learn to use add, has, and size, and distinguish sets from arrays and unions.