Importing from URLs in Deno - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the default export from a URL.

Deno

import myModule from "[1]";

Drag options to blanks, or click blank then click option'

A./localModule.ts

Bhttps://example.com/script.js

Cfs

Dhttps://deno.land/std@0.177.0/fs/mod.ts

Attempts:

3 left

💡 Hint

Common Mistakes

Using a local path instead of a URL.

Omitting the protocol (https://).

Using a bare module name without URL.

The import statement uses a full URL to load the module from the web in Deno.

2fill in blank

medium

Complete the code to import a named export from a URL.

Deno

import { serve } from "[1]";

Drag options to blanks, or click blank then click option'

Ahttps://deno.land/std@0.177.0/http/server.ts

Bhttps://deno.land/std@0.177.0/fs/mod.ts

Chttps://example.com/utils.ts

D./server.ts

Attempts:

3 left

💡 Hint

Common Mistakes

Importing from the wrong URL that doesn't export 'serve'.

Using a local file path instead of a URL.

Missing the curly braces for named imports.

The serve function is imported from the Deno standard HTTP server module URL.

3fill in blank

hard

Fix the error in the import statement to correctly import a module from a URL.

Deno

import [1] from "https://deno.land/std@0.177.0/fs/mod.ts";

Drag options to blanks, or click blank then click option'

A{ readFile }

BreadFile

C* as fs

Dfs

Attempts:

3 left

💡 Hint

Common Mistakes

Using default import syntax (no braces) for a named export.

Using namespace import syntax incorrectly.

Confusing named and default imports.

readFile is a named export from the fs module, so use curly braces: import { readFile } from "https://deno.land/std@0.177.0/fs/mod.ts";

4fill in blank

hard

Fill both blanks to import all exports as a namespace and use it.

Deno

import * as [1] from "https://deno.land/std@0.177.0/path/mod.ts";
console.log([2].basename("/foo/bar/baz.txt"));

Drag options to blanks, or click blank then click option'

Apath

Bfs

CpathModule

Dutils

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for import and usage.

Using unrelated names like 'fs' for path module.

Forgetting the '*' in import statement.

The namespace import is named path and used to call basename function.

5fill in blank

hard

Fill all three blanks to import a named export, rename it, and use it.

Deno

import { [1] as [2] } from "https://deno.land/std@0.177.0/fmt/colors.ts";
console.log([3]("Hello Deno"));

Drag options to blanks, or click blank then click option'

Ared

Bblue

CcolorRed

DcolorBlue

Attempts:

3 left

💡 Hint

Common Mistakes

Not renaming the import but using a different name in code.

Confusing the original and renamed names.

Using a name not imported.

The named export red is renamed to colorRed and used to color the text.

Practice

1. What is the main benefit of importing modules from URLs in Deno?

easy

A. You can use code directly from the web without installing it locally.

B. It makes your code run faster than local imports.

C. It automatically updates your code to the latest version.

D. It disables caching to always fetch fresh code.

Solution

1. Step 1: Understand URL imports in Deno

   Deno allows importing modules directly from web URLs, so you don't need to install packages locally.

2. Step 2: Identify the main benefit

   This feature simplifies using external code by fetching it on demand without manual installs.

3. Final Answer:

   You can use code directly from the web without installing it locally. -> Option A

4. Quick Check:

   Importing from URLs = No local install needed [OK]

Hint: Remember: URL imports mean no local installs needed [OK]

Common Mistakes:

• Thinking URL imports always update to latest code
• Believing URL imports disable caching
• Assuming URL imports make code run faster

2. Which of the following is the correct syntax to import a module from a URL in Deno?

easy

A. import { serve } from "https://deno.land/std/http/server.ts";

B. require("https://deno.land/std/http/server.ts");

C. import serve from "./server.ts";

D. load { serve } from "https://deno.land/std/http/server.ts";

Solution

1. Step 1: Recall Deno import syntax

   Deno uses ES module syntax with import { ... } from "url"; to import from URLs.

2. Step 2: Check each option

   import { serve } from "https://deno.land/std/http/server.ts"; uses correct ES module import syntax with a URL. require("https://deno.land/std/http/server.ts"); uses Node.js style require, which Deno does not use. import serve from "./server.ts"; imports locally, not from URL. load { serve } from "https://deno.land/std/http/server.ts"; uses invalid keyword load.

3. Final Answer:

   import { serve } from "https://deno.land/std/http/server.ts"; -> Option A

4. Quick Check:

   Correct import syntax = import { serve } from "https://deno.land/std/http/server.ts"; [OK]

Hint: Deno uses ES import syntax, not require or load [OK]

Common Mistakes:

• Using require() instead of import
• Trying to import local files with URL syntax
• Using invalid keywords like load

3. What will happen when you run this Deno code snippet?

import { serve } from "https://deno.land/std/http/server.ts";

console.log(typeof serve);

medium

A. "object"

B. "undefined"

C. Runtime error: Module not found

D. "function"

Solution

1. Step 1: Understand what is imported

   The serve function is exported from the URL module as a function.

2. Step 2: Check the typeof operator on serve

   Since serve is a function, typeof serve returns the string "function".

3. Final Answer:

   "function" -> Option D

4. Quick Check:

   typeof serve = "function" [OK]

Hint: Imported functions have typeof 'function' in JS/TS [OK]

Common Mistakes:

• Expecting 'undefined' if module loads correctly
• Thinking import causes runtime error
• Confusing function with object type

4. Identify the error in this Deno import statement:

import { serve } from "https://deno.land/std/http/server";

medium

A. URL must start with http:// not https://.

B. Using curly braces {} around serve is incorrect.

C. Missing file extension ".ts" in the URL.

D. Cannot import from URLs in Deno.

Solution

1. Step 1: Check URL correctness

   Deno requires full file paths including extensions for URL imports, so missing ".ts" causes error.

2. Step 2: Validate other parts

   Curly braces are correct for named imports. HTTPS is supported. Deno supports URL imports.

3. Final Answer:

   Missing file extension ".ts" in the URL. -> Option C

4. Quick Check:

   File extension required in URL imports [OK]

Hint: Always include file extensions in Deno URL imports [OK]

Common Mistakes:

• Omitting file extensions in import URLs
• Thinking HTTPS is unsupported
• Misunderstanding import syntax with braces

5. You want to ensure your Deno project always uses the same version of a library imported from a URL. Which practice helps achieve this?

hard

A. Disable Deno's cache to force fresh downloads every run.

B. Use a versioned URL like "https://deno.land/std@0.203.0/http/server.ts".

C. Manually download and import local copies only.

D. Import from the base URL without version to get latest updates.

Solution

1. Step 1: Understand versioning in URL imports

   Using versioned URLs locks the imported code to a specific release, ensuring stability.

2. Step 2: Evaluate options

   Use a versioned URL like "https://deno.land/std@0.203.0/http/server.ts". uses a versioned URL, which is best practice. Import from the base URL without version to get latest updates. fetches latest, risking breaking changes. Manually download and import local copies only. is manual and not URL import. Disable Deno's cache to force fresh downloads every run. disables caching, causing inefficiency.

3. Final Answer:

   Use a versioned URL like "https://deno.land/std@0.203.0/http/server.ts". -> Option B

4. Quick Check:

   Versioned URLs = stable imports [OK]

Hint: Lock versions in URL to keep imports stable [OK]

Common Mistakes:

• Using unversioned URLs expecting stability
• Disabling cache wastes time and bandwidth
• Confusing manual local imports with URL imports