array-merge.mjs

const ConflictSymbol = Symbol('conflict')
const isEmpty = x => x.length === 0
const conflicts = x => x[ConflictSymbol]
const hasConflicts = x => !isEmpty(x[ConflictSymbol])

const mergeArrays = (local, working, remote) => {
    const merged = [];

    merged[ConflictSymbol] = []

    remote.forEach((remoteValue, index) => {
        const localValue = local[index]
        const workingValue = working[index];

        if (localValue !== remoteValue && workingValue !== localValue) {
            merged[ConflictSymbol] = [...(merged[ConflictSymbol]), {
                index: index,
                local: localValue,
                working: workingValue,
                remote: remoteValue
            }]
        }

        // Merge: Prefer the working value if it's different from local, otherwise take remote
        merged[index] = (localValue === remoteValue) ? workingValue : remoteValue;
    })

    return merged
};