Glasgow | 26-ITP-May | Niangh Ciang | Sprint 1 | Exercises by Niangh-Ciang · Pull Request #1241 · CodeYourFuture/Module-Data-Groups

Niangh-Ciang · 2026-07-10T08:52:06Z

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

Completed Sprint 1 exercises.

LonMcGregor

Good work on these tasks. I have some questions in the comments to check you fully understand the solutions that you've written. Could you answer them please?

LonMcGregor · 2026-07-14T16:16:29Z

+  if (!Array.isArray(list)) {
+    return null;
+  }
+  const numbersOnly = list.filter((value) => typeof value === "number");


Do you know of any values which would pass this typeof check, but which are not actually numbers?

I researched more about this, and I now understand that NaN, Infinity, and -Infinity would all pass the typeof value === "number" check, even though they are not valid finite numbers. These values are treated as “number” by JavaScript’s typeof operator, so they would still be included by my current filter.

Good idea - is there an addition you can make to the filter that would catch these?

I changed the filter to list.filter(Number.isFinite) so NaN, Infinity, and -Infinity don’t get included.

LonMcGregor · 2026-07-14T16:16:50Z

+    return null;
+  }
+
+  const sortedList = [...numbersOnly].sort((a, b) => a - b);


What is the spread operator doing here?

The spread operator makes a copy of the numbersOnly array before sorting it. Because .sort() changes the original array, using [...numbersOnly] lets me sort a copy instead of modifying the original.

Does it matter if sort changes the original array? Why do you need to avoid that here?

Since numbersOnly is already a new array created by filter(), sorting it doesn’t modify the original list. That means the spread operator isn’t strictly necessary for this function to work. Using numbersOnly.sort((a, b) => a - b) would also pass all the tests — including the one that checks the input array is not changed (expect(list).toEqual([3, 1, 2])). I used [...numbersOnly] simply to avoid unexpected side effects

LonMcGregor · 2026-07-14T16:17:32Z

+      total += element;
+    }
+  }
+  total = Number(total.toFixed(2));


Why are you using toFixed here?

I used toFixed(2) to avoid floating‑point precision errors. In my decimal test (expect(sum([-5, 2.3, 7.5, 3.9, 2.1])).toEqual(10.8)), JavaScript produces 10.799999999999 instead of 10.8. Rounding to 2 decimal places ensures the test passes correctly, which is why I included it.

OK. This approach makes sense. Just be careful in future if you are working with arithmetic that you don't accidentally introduce inaccuracy by rounding more than you need to.

LonMcGregor · 2026-07-15T13:47:46Z

Good work - this task is done. Your reasoning for using [... array] makes sense, but I would suggest that if it's not strictly required you shouldn't use it as it adds a bit of unnecessary complexity to code.

Niangh-Ciang added 9 commits July 6, 2026 13:38

Fixed median.js implementation

a753854

Add dedupe tests

3cbe8a9

Implement dedupe function

f22f510

Add max tests

7b69ec9

Implement findMax and update tests

2e90135

Add test suite for sum function

c03e930

Implement sum function

650ead1

Refactor includes implementation

7fd5ba8

Implement final frequency calculation

5467d65

Niangh-Ciang added 📅 Sprint 1 Assigned during Sprint 1 of this module Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. Module-Data-Groups The name of the module. labels Jul 10, 2026

LonMcGregor added the Review in progress This review is currently being reviewed. This label will be replaced by "Reviewed" soon. label Jul 14, 2026

LonMcGregor reviewed Jul 14, 2026

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LonMcGregor added Reviewed Volunteer to add when completing a review with trainee action still to take. and removed Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. labels Jul 14, 2026

Niangh-Ciang added Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. and removed Reviewed Volunteer to add when completing a review with trainee action still to take. labels Jul 14, 2026

LonMcGregor added Reviewed Volunteer to add when completing a review with trainee action still to take. and removed Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. labels Jul 15, 2026

Fix median filter for invalid numeric values

1fbbc08

Niangh-Ciang mentioned this pull request Jul 17, 2026

Complete sprint 1 exercises Niangh-Ciang/My-Coursework-Planner#37

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Niangh-Ciang commented Jul 10, 2026

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LonMcGregor commented Jul 15, 2026

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