deno compile for standalone executables - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when you run a Deno compiled standalone executable?

You have compiled a Deno script into a standalone executable using deno compile. What will happen when you run this executable on a compatible system?

A It requires Deno to be installed to run the executable.

B It runs without needing Deno installed and executes the script's code.

C It only runs if you pass the <code>--allow-run</code> flag at runtime.

D It opens the Deno REPL instead of running the script.

💡 Hint

Think about what 'standalone' means for an executable.

A standalone executable created by deno compile bundles the Deno runtime and your script together. This means it can run on a system without Deno installed, just like any normal program.

📝 Syntax

intermediate

Which command correctly compiles a Deno script into a standalone executable named 'app'?

You want to compile app.ts into a standalone executable called app. Which command is correct?

A deno compile --output app app.ts

B deno compile app.ts --output app

C deno run --compile app.ts -o app

D deno build app.ts --output app

💡 Hint

Check the official deno compile syntax for output naming.

The correct syntax is deno compile --output app app.ts. The --output flag specifies the executable name, followed by the script file.

🔧 Debug

advanced

Why does the compiled executable fail with a permission error?

You compiled a Deno script that reads a file. When running the standalone executable, it throws a permission error. Why?

Deno

import { readTextFile } from "https://deno.land/std/fs/mod.ts";

const data = await Deno.readTextFile("secret.txt");
console.log(data);

A The file path is incorrect in the compiled executable.

B Deno scripts cannot read files when compiled.

C The executable lacks the necessary permission flags to read files.

D The executable must be run with <code>deno run</code> to access files.

💡 Hint

Think about how Deno handles permissions and how they apply to compiled executables.

Deno requires explicit permission flags to access files. When compiling, you must pass permission flags like --allow-read to the deno compile command so the executable has those permissions.

❓ state_output

advanced

What is the output of this compiled Deno executable?

Consider this Deno script compiled into a standalone executable and run on a system without Deno installed:

console.log("Hello from Deno!");

What will the executable print?

Deno

console.log("Hello from Deno!");

A Hello from Deno!

B No output, the executable does nothing

C Error: Deno runtime not found

D SyntaxError at runtime

💡 Hint

Think about what the compiled executable contains.

The compiled executable bundles the Deno runtime and your script, so it runs independently and prints the message as expected.

🧠 Conceptual

expert

Which statement about Deno compiled standalone executables is true?

Choose the correct statement about Deno standalone executables created with deno compile.

A They automatically update themselves when a new Deno version is released.

B They require the user to install Deno separately before running.

C They only work on the operating system where they were compiled, but not on others.

D They include the Deno runtime and can run without any external dependencies.

💡 Hint

Think about what 'standalone' means and how executables behave across systems.

Deno standalone executables bundle the runtime and script, so they run independently without needing Deno installed. However, they are platform-specific and do not auto-update.

Practice

1. What is the main purpose of the deno compile command?

easy

A. To create a standalone executable from a Deno script

B. To install Deno on your computer

C. To run a Deno script without compiling

D. To update Deno to the latest version

Solution

1. Step 1: Understand the role of deno compile

   This command packages a Deno script into a single executable file that can run without needing Deno installed.

2. Step 2: Compare other options

   Installing Deno, running scripts without compiling, or updating Deno are done by different commands, not deno compile.

3. Final Answer:

   To create a standalone executable from a Deno script -> Option A

4. Quick Check:

   deno compile = create executable [OK]

Hint: Remember: compile means make a runnable file [OK]

Common Mistakes:

• Confusing compile with install
• Thinking compile runs scripts directly
• Mixing compile with update commands

2. Which of the following is the correct syntax to compile a Deno script named app.ts into a standalone executable named app.exe on Windows?

easy

A. deno run --output app.exe app.ts

B. deno compile --output app.exe app.ts

C. deno build app.ts -o app.exe

D. deno compile app.ts --exe app.exe

Solution

1. Step 1: Recall the correct deno compile syntax

   The command uses deno compile --output [filename] [script] to specify output executable and source file.

2. Step 2: Check other options for errors

   deno run runs scripts but does not compile; deno build is not a valid command; --exe is not a recognized flag.

3. Final Answer:

   deno compile --output app.exe app.ts -> Option B

4. Quick Check:

   compile + --output + script = correct syntax [OK]

Hint: Use --output to name your executable [OK]

Common Mistakes:

• Using deno run instead of deno compile
• Wrong flag like --exe instead of --output
• Mixing command order

3. Given the command deno compile --output hello hello.ts and hello.ts contains console.log('Hello Deno!');, what will happen when you run the generated executable?

medium

A. It opens a browser window

B. It throws a syntax error

C. It does nothing

D. It prints 'Hello Deno!' to the console

Solution

1. Step 1: Understand the compiled executable behavior

   The executable runs the script code, so it will print the message to the console.

2. Step 2: Eliminate incorrect options

   No syntax error occurs because the script is valid; it does not open a browser or stay silent.

3. Final Answer:

   It prints 'Hello Deno!' to the console -> Option D

4. Quick Check:

   Compiled script output = printed message [OK]

Hint: Compiled executable runs script code as is [OK]

Common Mistakes:

• Expecting compile to change output
• Thinking compile causes errors
• Assuming GUI opens automatically

4. You tried to compile your script with deno compile --output myapp myapp.ts but got an error: PermissionDenied: read access to file 'myapp.ts' is required. What is the best way to fix this?

medium

A. Add --allow-read flag to the compile command

B. Run the command as administrator

C. Add --allow-run flag to the compile command

D. Rename the script file to myapp.js

Solution

1. Step 1: Understand the permission error

   The error says read access is denied for the script file, which is required to compile the source file.

2. Step 2: Identify correct permission flag

   --allow-read grants permission to read files, which is required to compile the script.

3. Final Answer:

   Add --allow-read flag to the compile command -> Option A

4. Quick Check:

   PermissionDenied = missing --allow-read [OK]

Hint: Use --allow-read to fix file access errors [OK]

Common Mistakes:

• Using --allow-run instead of --allow-read
• Thinking admin rights fix permission errors
• Renaming file without fixing permissions

5. You want to create a standalone executable for Linux from a Deno script server.ts on a Windows machine. Which command correctly compiles it for Linux?

hard

A. deno compile --output server-linux --platform linux server.ts

B. deno compile --output server-linux --os linux server.ts

C. deno compile --output server-linux --target x86_64-unknown-linux-gnu server.ts

D. deno compile --output server-linux --target linux-x64 server.ts

Solution

1. Step 1: Understand cross-compilation with deno compile

   You must specify the target triple for the desired OS and architecture using --target.

2. Step 2: Identify the correct target triple for Linux x64

   x86_64-unknown-linux-gnu is the standard target triple for 64-bit Linux.

3. Step 3: Check other options for invalid flags or values

   --platform and --os are not valid flags; linux-x64 is not a recognized target triple.

4. Final Answer:

   deno compile --output server-linux --target x86_64-unknown-linux-gnu server.ts -> Option C

5. Quick Check:

   Cross-compile uses --target with correct triple [OK]

Hint: Use --target with OS-arch triple for cross-compiling [OK]

Common Mistakes:

• Using invalid flags like --platform or --os
• Wrong target triple format
• Assuming compile auto-detects target OS