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London | 26-ITP-Sep | Sakiya Mayow | Sprint 1| coursework/data groups - #1504
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Code looks good. Good job.
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How should the function handle an array containing NaN?
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What should calculateMean([Infinity, 0, -Infinity]) or calculateMean([0, NaN]) return?
The same also applies to sum().
| test("given negative and decimal numbers, returns the correct mean", () => { | ||
| expect(calculateMean([-2, 3.5, 4.5])).toBe(2); | ||
| }); | ||
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Decimal numbers in most programming languages (including JS) are internally represented in "floating point number" format. Floating point arithmetic is not exact. For example, the result of 46.5678 - 46 === 0.5678 is false because 46.5678 - 46 only yield a value that is very close to 0.5678. Even changing the order in which the program add/subtract numbers can yield different values.
So the following could happen
expect( 1.2 + 0.6 + 0.005 ).toEqual( 1.805 ); // This fail
expect( 1.2 + 0.6 + 0.005 ).toEqual( 1.8049999999999997 ); // This pass
expect( 0.005 + 0.6 + 1.2 ).toEqual( 1.8049999999999997 ); // This fail
console.log(1.2 + 0.6 + 0.005 == 1.805); // false
console.log(1.2 + 0.6 + 0.005 == 0.005 + 0.6 + 1.2); // falseSuggestion: Look up
- Checking equality in floating point arithmetic in JavaScript
- Checking equality in floating point arithmetic with Jest
| // Refactor the implementation of includes to use a for...of loop | ||
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| function includes(list, target) { | ||
| for (let index = 0; index < list.length; index++) { | ||
| const element = list[index]; | ||
| if (element === target) { | ||
| return true; | ||
| } | ||
| } |
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Note: The objective of this exercise is to change the normal for-loop to for-of-loop (per the Instruction on line 1), as oppose to totally rewrite the whole function.
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Task code
CYF-1071
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This PR includes Fix, Implement and Refactor exercises. It includes fixing existing functions, implementing new functions and refactoring code to make it simpler and cleaner while ensuring the tests pass.