Template partials and layouts in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to render a view using a layout in Express with EJS.

Express

app.get('/', (req, res) => {
  res.render('index', { layout: '[1]' });
});

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

A'main-layout'

B'index-layout'

C'default-layout'

D'base-layout'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to pass the layout option.

Using a layout name that does not exist.

The layout option specifies which layout file to use when rendering the view. 'main-layout' is a common default name.

2fill in blank

medium

Complete the EJS code to include a partial header template inside a layout.

Express

<header>
  <%- include([1]) %>
</header>

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

A'partials/footer.ejs'

B'partials/sidebar.ejs'

C'layouts/main.ejs'

D'partials/header.ejs'

Attempts:

3 left

💡 Hint

Common Mistakes

Including the wrong partial file.

Forgetting quotes around the partial path.

The include statement inserts the content of the specified partial file. Here, the header partial is included.

3fill in blank

hard

Fix the error in the EJS layout to correctly render the body content.

Express

<body>
  [1]
</body>

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

A<%== body %>

B<%= body %>

C<%- body %>

D<% body %>

Attempts:

3 left

💡 Hint

Common Mistakes

Using <%= body %> which escapes HTML.

Using <% body %> which does not output content.

Using <%- body %> outputs unescaped HTML content, which is needed to render the body correctly in layouts.

4fill in blank

hard

Fill both blanks to create a layout that includes a header partial and renders the body content.

Express

<html>
  <body>
    <header>
      <%- include([1]) %>
    </header>
    <main>
      [2]
    </main>
  </body>
</html>

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

A'partials/header.ejs'

B<%- body %>

C<%= body %>

D'partials/footer.ejs'

Attempts:

3 left

💡 Hint

Common Mistakes

Using escaped output for body content.

Including the wrong partial file.

The header partial is included with include('partials/header.ejs'). The body content is rendered unescaped with <%- body %>.

5fill in blank

hard

Fill all three blanks to create an Express route that renders a view with a layout and includes a footer partial in the layout.

Express

app.get('/about', (req, res) => {
  res.render('about', { layout: [1] });
});

// In layout file:
<footer>
  <%- include([2]) %>
</footer>

// In about.ejs:
<h1>[3]</h1>

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

A'main-layout'

B'partials/footer.ejs'

CAbout Us

D'partials/header.ejs'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong layout name.

Including header instead of footer partial.

Forgetting quotes around strings.

The route renders 'about' view with 'main-layout'. The layout includes the footer partial. The about view shows the heading 'About Us'.

Practice

1. What is the main purpose of using template partials in Express apps?

easy

A. To define the main layout structure for all pages

B. To reuse small template parts like headers or footers across pages

C. To write JavaScript logic inside templates

D. To connect the app to a database

Solution

1. Step 1: Understand what partials are

   Partials are small pieces of templates like headers or footers that you can reuse.

2. Step 2: Differentiate partials from layouts

   Layouts provide the main page structure, while partials are smaller reusable parts inside layouts or pages.

3. Final Answer:

   To reuse small template parts like headers or footers across pages -> Option B

4. Quick Check:

   Partials = reusable small template parts [OK]

Hint: Partials = small reusable pieces like header/footer [OK]

Common Mistakes:

• Confusing partials with layouts
• Thinking partials define full page structure
• Assuming partials handle backend logic

2. Which syntax correctly includes a partial named header in an EJS template?

easy

A. <%- include('header') %>

B. <%= partial('header') %>

C. <% include header %>

D. <@include header>

Solution

1. Step 1: Recall EJS partial include syntax

   EJS uses <%- include('partialName') %> to include partials with unescaped output.

2. Step 2: Check each option

   <%- include('header') %> matches the correct syntax with parentheses and quotes around 'header'.

3. Final Answer:

   <%- include('header') %> -> Option A

4. Quick Check:

   EJS partial include = <%- include('name') %> [OK]

Hint: EJS partials use <%- include('name') %> syntax [OK]

Common Mistakes:

• Omitting quotes or parentheses in include
• Using <%= instead of <%- for unescaped output
• Confusing syntax with other template engines

3. Given this Express setup using EJS with a layout:

app.set('view engine', 'ejs');

// In route handler:
res.render('index', { title: 'Home' });

And the layout layout.ejs contains:

<html>
<head><title><%= title %></title></head>
<body>
<%- body %>
</body>
</html>

If index.ejs has <h1>Welcome</h1>, what will the rendered HTML look like?

medium

A. Welcome

B. Home<h1>Welcome</h1>

C. HomeWelcome

D. Error: body is undefined

Solution

1. Step 1: Understand layout and body insertion

   The layout uses <%- body %> to insert the rendered content of index.ejs unescaped.

2. Step 2: Check variable substitution

   The title variable is passed as 'Home', so <%= title %> becomes 'Home'. The body inserts <h1>Welcome</h1> as HTML.

3. Final Answer:

   <html><head><title>Home</title></head><body><h1>Welcome</h1></body></html> -> Option C

4. Quick Check:

   Layout inserts title and body correctly [OK]

Hint: Layout inserts body unescaped with <%- body %> [OK]

Common Mistakes:

• Using escaped output <%= body %> causing HTML to show as text
• Not passing title variable to template
• Assuming body variable is automatic without layout support

4. You try to use a layout in Express with EJS but get an error: ReferenceError: body is not defined. What is the likely cause?

medium

A. You forgot to use a layout engine or middleware that injects the body content

B. You used <%= body %> instead of <%- body %>

C. You named your layout file incorrectly

D. You did not install EJS package

Solution

1. Step 1: Understand how layouts work in Express with EJS

   EJS alone does not support layouts natively; you need middleware like express-ejs-layouts to inject body content.

2. Step 2: Identify cause of ReferenceError

   If body is undefined, it means the layout engine or middleware that sets body is missing or not configured.

3. Final Answer:

   You forgot to use a layout engine or middleware that injects the body content -> Option A

4. Quick Check:

   Missing layout middleware = body undefined error [OK]

Hint: Layouts need middleware to define body variable [OK]

Common Mistakes:

• Assuming EJS supports layouts without extra setup
• Confusing escaped vs unescaped output errors
• Ignoring middleware installation or configuration

5. You want to create a consistent site with a header, footer, and main content area using Express and EJS. Which approach best uses partials and layouts together?

hard

A. Use only partials for header, footer, and content without any layout file

B. Include header and footer partials directly in every page template without a layout

C. Write all HTML in each page template without partials or layouts

D. Create a layout.ejs with header and footer partials included, and insert page content in a <%- body %> area

Solution

1. Step 1: Understand roles of layouts and partials

   Layouts provide the main page structure; partials are reusable pieces like header and footer.

2. Step 2: Combine layout and partials for best practice

   Put header and footer partials inside the layout, then insert page-specific content in the body area.

3. Final Answer:

   Create a layout.ejs with header and footer partials included, and insert page content in a <%- body %> area -> Option D

4. Quick Check:

   Layout + partials = clean, consistent site structure [OK]

Hint: Use layout for structure, partials for reusable parts [OK]

Common Mistakes:

• Duplicating header/footer in every page instead of partials
• Skipping layout causing inconsistent page structure
• Mixing content and layout roles improperly