JavaScript Grouped Scores Filter: Two Approaches Quiz

Filter a grouped scores object so each row keeps only requested keys, solved two ways (Object.entries + map and a for-in loop), plus companions on Map output and key-rename mapping.

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JavaScript

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arrays

hash-map

array-manipulation-patterns

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Implement showOnly(obj, keys) using Object.entries(obj) + Array.prototype.map so each group is rewritten as a new array of objects that contain only the requested keys (skip keys that are missing on a row).

Examples

Example 1:

Input:
scores = {
  groupA: [
    { score1: '123', score2: '2222', score3: '1321' },
    { score1: '234', score2: '44',   score3: '11221' }
  ],
  groupB: [
    { score1: '222', score2: '1717', score3: '131' },
    { score2: '2566', score3: '433' }
  ]
}
keys = ['score1', 'score3']
Output:
{
  groupA: [ { score1: '123', score3: '1321' }, { score1: '234', score3: '11221' } ],
  groupB: [ { score1: '222', score3: '131' }, { score3: '433' } ]
}
Explanation: Missing keys are silently omitted instead of producing `undefined` properties.

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