Data Merging

Requirements

• Export mergeData as named and default. Input is an array of { user: number, equipment: string[] } records. User IDs are finite integers; equipment names are strings.
• Return one new row per distinct user, in first-appearance order. Each row’s equipment list contains distinct names in first-appearance order across that user’s rows.
• Names are case-sensitive. Keep empty strings if present. Include users with empty equipment lists.
• Create a new output array, row objects, and equipment arrays. Do not mutate input rows or their arrays. Extra row fields and invalid inputs are outside scope.
• Use a Map and a Set, or an equally efficient approach: avoid repeatedly scanning all output rows or using includes for every equipment entry.

Examples

Input: mergeData([{ user: 2, equipment: ["camera", "mic"] }, { user: 1, equipment: [] }, { user: 2, equipment: ["mic", "light"] }])
Output: [{ user: 2, equipment: ["camera", "mic", "light"] }, { user: 1, equipment: [] }]

Input: mergeData([])
Output: []