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⚡ Bolt: Optimize statistics calculation by combining array iterations #157

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⚡ Bolt: Optimize statistics calculation by combining array iterations #157

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17 changes: 11 additions & 6 deletions frontend/dashboard.js
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Original file line number Diff line number Diff line change
Expand Up @@ -130,19 +130,24 @@ function updateStatistics(subjects) {
return;
}

const scores = subjects.map(subject => subject.scoreValue);
const highest = Math.max(...scores);

// 計算加權平均
// Combine max calculation and weighted average into a single pass
// to avoid multiple O(n) iterations and Math.max spread limitations.
let highest = -Infinity;
let totalWeightedScore = 0;
let totalWeight = 0;

subjects.forEach(subject => {
for (let i = 0; i < subjects.length; i++) {
const subject = subjects[i];
Comment on lines +133 to +140

Copilot AI Apr 9, 2026

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updateStatistics behavior changed but there are no unit tests covering statistics computation (avg/highest/total). Since this file already has tests for other helpers, consider adding a small DOM-based test (e.g., via JSDOM) to assert avgScore/highestScore updates for representative subject arrays, including large arrays and edge values.

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const score = subject.scoreValue;

if (score > highest) {
highest = score;
}

Comment on lines +135 to +146

Copilot AI Apr 9, 2026

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highest is initialized to -Infinity and only updated via score > highest. If any subject.scoreValue is NaN (possible via getNumericScore returning Number(fallbackValue) without a NaN guard), comparisons will always be false and highest can remain -Infinity (or ignore NaNs), which changes behavior vs Math.max(...scores) (would produce NaN). Consider explicitly handling non-finite scores (e.g., track a hasValidScore/hasNaN flag and set the UI to '--' or propagate NaN consistently) so highestScore never renders -Infinity.

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const weight = getSubjectWeight(subject.SubjectName);
totalWeightedScore += score * weight;
totalWeight += weight;
});
}
Comment on lines +139 to +150

@gemini-code-assist gemini-code-assist Bot Apr 9, 2026

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medium

For better readability and consistency with other parts of the codebase that use declarative iteration (e.g., forEach), consider using a for...of loop, as the index i is not used. This more clearly expresses the intent to iterate over the elements of the array.

Additionally, this change introduces a different behavior for the edge case where all scores are NaN. The previous Math.max(...scores) would result in NaN. With the new logic, highest will remain -Infinity and be rendered to the UI. This is likely not the desired outcome. You may want to handle this case after the loop by checking if highest is still -Infinity and setting it to a more user-friendly value like '--'.

    for (const subject of subjects) {
        const score = subject.scoreValue;

        if (score > highest) {
            highest = score;
        }

        const weight = getSubjectWeight(subject.SubjectName);
        totalWeightedScore += score * weight;
        totalWeight += weight;
    }


const weightedAvg = totalWeight > 0 ? totalWeightedScore / totalWeight : 0;

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