Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 2 | Data Groups by Richiealx · Pull Request #1042 · CodeYourFuture/Module-Data-Groups

Richiealx · 2026-03-18T21:41:38Z

Learners, PR Template

Self checklist

I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
My changes meet the requirements of the task
I have tested my changes
My changes follow the style guide

Changelist

This pull request contains my completed work for Sprint 2 - Data Groups.

Debug

Fixed address.js (correct object property access)
Fixed author.js (correct object iteration)
Fixed recipe.js (proper formatting of output)

Implement

Implemented contains using own-property checking (avoids inherited properties)
Implemented createLookup to convert key-value pairs into an object
Implemented tally using Object.create(null) to handle edge cases like "toString"
Improved parseQueryString to:
- handle values containing "="
- handle missing values and keys
- ignore trailing "&"
- decode URL-encoded keys and values

Interpret

Analysed and explained the issue in invert.js
Fixed implementation using bracket notation
Added tests to verify correctness

Stretch

Implemented countWords with:
- punctuation handling
- case normalisation
- whitespace handling
- safe object creation to handle words like "constructor"
Refactored calculateMode into smaller helper functions:
- frequency tracking
- mode selection

Testing

All tests pass successfully
7 test suites and 27 tests passing

cjyuan

Code looks good. I just have some suggestions.

cjyuan · 2026-03-21T11:50:12Z

Sprint-2/debug/recipe.js

+for (const ingredient of recipe.ingredients) {
+  console.log(ingredient);
+}


Since ingredient values are separated by '\n' in the output, we could also use Array.prototype.join() to construct the equivalent string and then output the resulting string.

cjyuan · 2026-03-21T11:52:53Z

Sprint-2/implement/contains.js

+  }
+
+  // Check if the object has the property as its own key
+  return Object.prototype.hasOwnProperty.call(obj, propertyName);


Could also use Object.hasOwn().

cjyuan · 2026-03-21T12:03:17Z

Sprint-2/implement/contains.js

+  // Validate propertyName
+  if (typeof propertyName !== "string" || propertyName.length === 0) {
+    return false;
+  }


Values of non-string type can be used as property names; they are just implicitly converted to equivalent strings. For example,

let obj = {}; obj[3.0] = 12; // 3.0 is treated as "3" when used as key console.log(obj["3"]); // output 12 console.log(obj[4-1]); // output 12 too console.log(Object.hasOwn(obj, 3)); // output true

Empty string can also serve as key.

cjyuan · 2026-03-21T12:16:42Z

Sprint-2/implement/querystring.js

+    // Extract the key and everything after the first "=" as the value
+    const key = pair.slice(0, separatorIndex);
+    const value = pair.slice(separatorIndex + 1);
+
    queryParams[key] = value;


No change required.

Note:

In real query string, both key and value are percent-encoded or URL encoded in the URL.
For example, the string "5%" is encoded as "5%25". So to get the actual value of "5%25"
(whether it is a key or value in the query string), we need to call a function to decode it.

You can also explore the URLSearchParams API.

cjyuan · 2026-03-21T12:17:13Z

Sprint-2/implement/tally.js

+  const counts = {};
+
+  // Loop through each item in the array
+  for (const item of items) {
+    // If the item already exists in the object, increase the count
+    if (counts[item]) {
+      counts[item] += 1;
+    } else {
+      // Otherwise initialise it
+      counts[item] = 1;
+    }
+  }
+
+  return counts;


Does the following function call returns the value you expect?

tally(["toString", "toString"]);

Suggestion: Look up an approach to create an empty object with no inherited properties.

Hi @cjyuan,

Thank you for your feedback.

I’ve now updated my implementation to address all the points raised:

Updated contains to use proper own-property checking and improved the tests to cover inherited properties, arrays, non-string keys, and edge cases

Fixed tally by using an object with no inherited properties and added an edge-case test for values like "toString"

Improved querystring to handle URL decoding and additional edge cases

Replaced the remaining test.todo in lookup.test.js with full test coverage, including validation and malformed input cases

Reviewed recipe.js and applied the suggested improvement using join for cleaner output

All test suites are now passing with no remaining TODO tests.
I also corrected the branch issue so this PR now only contains Sprint-2 files.

Thanks again for the helpful suggestions.

cjyuan · 2026-03-23T21:02:49Z

On this PR branch, I don't see any changes made to the files in the Sprint-2 folder (since my previous review).

That is, I don't see some of the changes which you said you did:

Updated contains to use proper own-property checking and improved the tests to cover inherited properties, arrays, non-string keys, and edge cases

Fixed tally by using an object with no inherited properties and added an edge-case test for values like "toString"

Improved querystring to handle URL decoding and additional edge cases

Reviewed recipe.js and applied the suggested improvement using join for cleaner output

Richiealx · 2026-03-24T01:26:09Z

Thank you for pointing that out.

You were right. Those specific changes were not yet present on the Sprint-2 PR branch. I’ve now updated the Sprint-2 files to include the requested fixes:

updated contains to use proper own-property checking and improved the tests to cover inherited properties, arrays, non-string keys, and empty-string keys
fixed tally to use an object with no inherited properties and added the "toString" edge-case test
improved querystring to handle URL decoding and added an extra decoding test
updated recipe.js to use join() for cleaner ingredient output

I also fixed countWords so the full Sprint-2 test suite passes cleanly.

All Sprint-2 tests are now passing on this PR branch:

7 test suites passed
36 tests passed

Richiealx added 10 commits March 18, 2026 19:25

Fix address debug exercise

95c4e75

Fix author debug exercise

a4f6039

Fix recipe debug exercise

6543d0f

Implement contains function and tests

eb9641b

Implement lookup function and tests

de8ca14

Implement tally function and tests

ce21823

Fix querystring parser and add edge case tests

7aa84ed

Fix invert implementation and add tests

af702c4

Complete stretch exercises for Sprint 2

12fb231

Fix test file location for countWords

e296ae7

Richiealx added the Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. label Mar 18, 2026

Address mentor feedback for sprint 1 data groups

a22ed15

cjyuan reviewed Mar 21, 2026

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Remove Sprint-1 files from Sprint-2 PR

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Apply mentor feedback to Sprint 2 files

4b01ab0

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Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 2 | Data Groups#1042

Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 2 | Data Groups#1042
Richiealx wants to merge 13 commits intoCodeYourFuture:mainfrom
Richiealx:coursework/sprint-2-data-groups

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Richiealx commented Mar 18, 2026

Learners, PR Template

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