Redirect and rewrite rules in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a redirect rule in Firebase Hosting?

A redirect rule sends visitors from one URL to another URL automatically. It changes the address shown in the browser.

beginner

What does a rewrite rule do in Firebase Hosting?

A rewrite rule serves content from a different location without changing the URL in the browser. It keeps the original URL visible.

intermediate

How do you define a redirect rule in Firebase Hosting configuration?

You add a 'redirects' section in firebase.json with 'source' (the URL to match) and 'destination' (where to send users), plus a 'type' for HTTP status code.

intermediate

Why use rewrite rules for single-page applications (SPA)?

Rewrite rules send all URL requests to the SPA's main index.html file, so the app can handle routing internally without server errors.

beginner

What HTTP status code is commonly used for permanent redirects in Firebase?

The HTTP status code 301 is used for permanent redirects, telling browsers and search engines the change is permanent.

In Firebase Hosting, what happens when you set a rewrite rule?

A The site reloads with a 404 error

B The browser URL changes to the new destination

C The user is blocked from accessing the site

D The URL in the browser stays the same but content is served from another location

Rewrite rules serve content from a different location without changing the browser's URL.

Which section in firebase.json defines redirect rules?

A headers

B redirects

C rewrites

D functions

Redirect rules are defined under the 'redirects' section in firebase.json.

What HTTP status code should you use for a temporary redirect in Firebase?

A 301

B 404

C 302

D 500

302 is the HTTP status code for temporary redirects.

Why are rewrite rules important for SPAs hosted on Firebase?

A They allow the app to handle routing without server errors

B They block unwanted users

C They speed up image loading

D They change the URL to a new domain

Rewrite rules send all requests to index.html so the SPA can manage routing internally.

Which Firebase Hosting feature changes the URL shown in the browser?

A Redirect rules

B Rewrite rules

C Headers

D Caching

Redirect rules change the browser URL to the new destination.

Explain the difference between redirect and rewrite rules in Firebase Hosting.

Think about what the user sees in the browser address bar.

Describe how you would configure Firebase Hosting to support a single-page application using rewrite rules.

Consider how SPAs handle navigation internally.

Practice

1. What is the main difference between a redirect and a rewrite in Firebase Hosting?

easy

A. Redirect changes the browser URL, rewrite does not change the URL shown.

B. Rewrite changes the browser URL, redirect does not change the URL shown.

C. Both redirect and rewrite always change the browser URL.

D. Neither redirect nor rewrite affect the browser URL.

Solution

1. Step 1: Understand redirect behavior

   A redirect sends the user to a new URL and updates the browser address bar to show this new URL.

2. Step 2: Understand rewrite behavior

   A rewrite serves different content but keeps the original URL visible in the browser address bar.

3. Final Answer:

   Redirect changes the browser URL, rewrite does not change the URL shown. -> Option A

4. Quick Check:

   Redirect updates URL, rewrite keeps URL same [OK]

Hint: Redirect changes URL, rewrite hides content change [OK]

Common Mistakes:

• Confusing redirect with rewrite behavior
• Thinking rewrite changes browser URL
• Assuming redirect does not update URL

2. Which of the following is the correct Firebase Hosting syntax to redirect from /old-page to /new-page?

easy

A. "redirect": [{"source": "/old-page", "destination": "/new-page"}]

B. "rewrites": [{"source": "/old-page", "destination": "/new-page"}]

C. "rewrites": [{"source": "/old-page", "type": 301, "destination": "/new-page"}]

D. "redirects": [{"source": "/old-page", "destination": "/new-page", "type": 301}]

Solution

1. Step 1: Identify redirect syntax

   Redirects require a source, destination, and a type (like 301 for permanent redirect).

2. Step 2: Check options for correct syntax

   "redirects": [{"source": "/old-page", "destination": "/new-page", "type": 301}] correctly includes source, destination, and type 301. Others miss type or use rewrites incorrectly.

3. Final Answer:

   "redirects": [{"source": "/old-page", "destination": "/new-page", "type": 301}] -> Option D

4. Quick Check:

   Redirect needs type code like 301 [OK]

Hint: Redirects need a type code (301 or 302) [OK]

Common Mistakes:

• Omitting the redirect type code
• Using rewrites instead of redirects for URL change
• Placing type in rewrites block

3. Given this Firebase Hosting config snippet:

{
  "rewrites": [
    {"source": "/app/**", "destination": "/index.html"}
  ]
}

What happens when a user visits /app/profile?

medium

A. The browser URL stays /app/profile but serves content from /index.html.

B. The browser URL changes to /index.html and shows that page.

C. The browser URL changes to /app/index.html and shows that page.

D. The browser returns a 404 error because /app/profile does not exist.

Solution

1. Step 1: Understand rewrite with wildcard

   The rewrite rule matches any URL starting with /app/ and serves /index.html content without changing the URL.

2. Step 2: Apply to /app/profile

   Visiting /app/profile triggers the rewrite, so content from /index.html is served but URL remains /app/profile.

3. Final Answer:

   The browser URL stays /app/profile but serves content from /index.html. -> Option A

4. Quick Check:

   Rewrite serves content without URL change [OK]

Hint: Rewrite serves content but keeps URL same [OK]

Common Mistakes:

• Thinking rewrite changes the URL
• Expecting 404 error for unmatched files
• Assuming redirect happens instead of rewrite

4. You wrote this Firebase Hosting config:

{
  "redirects": [
    {"source": "/home", "destination": "/index.html"}
  ]
}

But the redirect does not work as expected. What is the problem?

medium

A. Using redirects instead of rewrites for serving index.html.

B. The source path should be /home/** to match all subpaths.

C. Missing the redirect type (301 or 302) in the redirect rule.

D. The destination should be a full URL, not a relative path.

Solution

1. Step 1: Analyze the redirect behavior

   A redirect requires a type (301 or 302) to work properly. Missing the type causes the redirect to fail.

2. Step 2: Identify the likely expectation and fix

   Adding the redirect type (301 or 302) will fix the redirect. Using rewrites is an alternative if you want to serve content without changing the URL.

3. Final Answer:

   Missing the redirect type (301 or 302) in the redirect rule. -> Option C

4. Quick Check:

   Redirect requires type code [OK]

Hint: Redirects need a type code (301 or 302) [OK]

Common Mistakes:

• Using redirects instead of rewrites to preserve URL
• Confusing redirects with rewrites
• Using relative paths incorrectly

5. You want to support a single-page app on Firebase Hosting where all URLs under /app/ show index.html content without changing the URL, but also redirect /old-app permanently to /app/. Which config snippet correctly achieves this?

hard

A. {
"rewrites": [
{"source": "/old-app", "destination": "/app/"},
{"source": "/app/**", "destination": "/index.html"}
]
}

B. {
"redirects": [
{"source": "/old-app", "destination": "/app/", "type": 301}
],
"rewrites": [
{"source": "/app/**", "destination": "/index.html"}
]
}

C. {
"redirects": [
{"source": "/old-app/**", "destination": "/app/", "type": 302}
],
"rewrites": [
{"source": "/app/**", "destination": "/index.html"}
]
}

D. {
"redirects": [
{"source": "/old-app", "destination": "/index.html", "type": 301}
],
"rewrites": [
{"source": "/app/**", "destination": "/app/"}
]
}

Solution

1. Step 1: Redirect /old-app to /app/ permanently

   Use a redirect with type 301 from /old-app to /app/ to update browser URL.

2. Step 2: Rewrite all /app/** URLs to serve index.html without changing URL

   Use a rewrite rule matching /app/** to serve /index.html content while keeping URL unchanged.

3. Step 3: Verify option correctness

   { "redirects": [ {"source": "/old-app", "destination": "/app/", "type": 301} ], "rewrites": [ {"source": "/app/**", "destination": "/index.html"} ] } correctly combines a 301 redirect and a rewrite for SPA support. Others misuse rewrites or redirect types.

4. Final Answer:

   { "redirects": [ {"source": "/old-app", "destination": "/app/", "type": 301} ], "rewrites": [ {"source": "/app/**", "destination": "/index.html"} ] } -> Option B

5. Quick Check:

   Redirect updates URL, rewrite serves SPA content [OK]

Hint: Redirect for URL change, rewrite for SPA content [OK]

Common Mistakes:

• Using rewrite instead of redirect for URL change
• Missing redirect type or using wrong type
• Rewriting to wrong destination path