TypeScript Compiler Installation and Setup - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output after compiling and running this TypeScript code?

Consider this TypeScript code snippet. After compiling it with the TypeScript compiler and running the resulting JavaScript, what will be printed to the console?

Typescript

const greet = (name: string): string => {
  return `Hello, ${name}!`;
};

console.log(greet("Alice"));

A Hello, Alice!

B greet("Alice")

C Error: name is not defined

D undefined

💡 Hint

Think about what the function returns and what console.log prints.

The function greet returns the string 'Hello, Alice!'. When compiled and run, console.log prints this string to the console.

🧠 Conceptual

intermediate

Which command installs the TypeScript compiler globally?

You want to install the TypeScript compiler so you can use the 'tsc' command anywhere on your computer. Which command should you run?

A npm install typescript@latest

B npm install -g typescript

C npm install --save-dev typescript

D npm install typescript

💡 Hint

Global installation allows using the command in any folder.

The '-g' flag installs the package globally, making the 'tsc' command available everywhere.

🔧 Debug

advanced

What error occurs when compiling this TypeScript code?

Look at this TypeScript code. When you run 'tsc' to compile it, what error will the compiler show?

Typescript

let count: number = "five";
console.log(count);

A ReferenceError: count is not defined

B SyntaxError: Unexpected string

C Type 'string' is not assignable to type 'number'.

D No error, compiles successfully

💡 Hint

Check the type assigned to 'count' and the declared type.

The variable 'count' is declared as a number but assigned a string, causing a type error.

📝 Syntax

advanced

Which command compiles all TypeScript files in the current folder using a config file?

You have a 'tsconfig.json' file in your project folder. Which command compiles all TypeScript files according to this config?

A tsc -p tsconfig.json

B tsc --project tsconfig.json

C tsc --config tsconfig.json

D tsc --all

💡 Hint

The '-p' flag specifies the project config file.

The '-p' or '--project' flag tells 'tsc' to use the given config file to compile the project.

🚀 Application

expert

How many JavaScript files are generated after compiling this project?

You have a project with these files: 'app.ts', 'utils.ts', and 'data.ts'. Your 'tsconfig.json' has "outDir": "dist" and "include": ["*.ts"]. After running 'tsc -p tsconfig.json', how many JavaScript files will appear in the 'dist' folder?

A 3

B 0

C 1

D Depends on the content of the files

💡 Hint

Each TypeScript file compiles to one JavaScript file unless excluded.

All three '.ts' files are included and compiled, producing three '.js' files in the output folder.

Practice

1. What command do you use to install the TypeScript compiler globally on your system?

easy

A. npm install typescript

B. tsc install

C. npm install -g typescript

D. install typescript -g

Solution

1. Step 1: Understand global installation

   To use TypeScript compiler anywhere, it must be installed globally using npm with the -g flag.

2. Step 2: Identify correct npm command

   The correct command is npm install -g typescript which installs TypeScript globally.

3. Final Answer:

   npm install -g typescript -> Option C

4. Quick Check:

   Global install uses npm install -g [OK]

Hint: Use npm install -g to install global packages [OK]

Common Mistakes:

• Forgetting the -g flag for global install
• Using 'tsc install' which is invalid
• Installing locally without -g

2. Which of the following commands correctly compiles a TypeScript file named app.ts into JavaScript?

easy

A. tsc app.js

B. tsc app.ts

C. npm run app.ts

D. compile app.ts

Solution

1. Step 1: Identify the TypeScript compiler command

   The TypeScript compiler command is tsc followed by the TypeScript file name.

2. Step 2: Match the correct file extension

   We must compile the .ts file, so the command is tsc app.ts.

3. Final Answer:

   tsc app.ts -> Option B

4. Quick Check:

   Compile with tsc filename.ts [OK]

Hint: Use tsc followed by .ts filename to compile [OK]

Common Mistakes:

• Trying to compile .js files with tsc
• Using npm run instead of tsc
• Typing wrong command like 'compile'

3. After installing TypeScript globally, what will be the output of the command tsc --version if the installed version is 5.1.3?

medium

A. TypeScript 5.1.3

B. tsc version: 5.1.3

C. 5.1.3

D. Version 5.1.3

Solution

1. Step 1: Understand tsc --version output format

   The tsc --version command outputs 'TypeScript 5.1.3'.

2. Step 2: Match output to options

   Only 'TypeScript 5.1.3' matches the exact output format.

3. Final Answer:

   TypeScript 5.1.3 -> Option A

4. Quick Check:

   tsc --version outputs 'TypeScript X.Y.Z' [OK]

Hint: tsc --version shows 'TypeScript X.Y.Z' [OK]

Common Mistakes:

• Expecting only the version number without 'TypeScript ' prefix
• Confusing output with npm version output
• Adding extra text like 'Version'

4. You run tsc app.ts but get an error: tsc: command not found. What is the most likely cause?

medium

A. Node.js is not installed

B. app.ts file has syntax errors

C. You need to run npm start instead

D. TypeScript is not installed globally or PATH is not set

Solution

1. Step 1: Analyze the error message

   The error 'tsc: command not found' means the system cannot find the TypeScript compiler command.

2. Step 2: Identify cause of missing command

   This usually happens if TypeScript is not installed globally or the system PATH does not include the location of tsc.

3. Final Answer:

   TypeScript is not installed globally or PATH is not set -> Option D

4. Quick Check:

   Command not found means missing install or PATH [OK]

Hint: Check if tsc is installed globally and in PATH [OK]

Common Mistakes:

• Assuming syntax errors cause command not found
• Trying npm start which is unrelated
• Thinking Node.js absence causes this error

5. You want to compile multiple TypeScript files in a project folder without typing each filename. Which setup helps you compile all files at once?

hard

A. Create a tsconfig.json file and run tsc without arguments

B. Run tsc *.ts in the terminal

C. Install TypeScript locally and run npm compile

D. Use tsc --all command

Solution

1. Step 1: Understand how to compile multiple files

   TypeScript uses a tsconfig.json file to configure project compilation settings for multiple files.

2. Step 2: Use tsc with tsconfig.json

   Running tsc without arguments reads tsconfig.json and compiles all files specified there.

3. Final Answer:

   Create a tsconfig.json file and run tsc without arguments -> Option A

4. Quick Check:

   tsconfig.json enables project-wide compilation [OK]

Hint: Use tsconfig.json and run tsc alone to compile all [OK]

Common Mistakes:

• Trying to use wildcard *.ts which may not work in all shells
• Assuming npm compile is a default command
• Using non-existent tsc --all option