@connectv/core/dist/es6/util/keyed-array-diff.js

agent-based reactive programming library for typescript/javascript

export function diff(value, oldKeyMap, keyfunc) {
    const additions = [];
    const deletions = [];
    const moves = [];
    const newKeyMap = Object.entries(value).reduce((map, [index, item]) => {
        const _key = keyfunc(item);
        map[_key] = { index, item };
        if (!(_key in oldKeyMap))
            additions.push({ index, item });
        return map;
    }, {});
    Object.entries(oldKeyMap).forEach(([_key, entry]) => {
        if (!(_key in newKeyMap))
            deletions.push(entry);
        else {
            const _newEntry = newKeyMap[_key];
            if (_newEntry.index != entry.index)
                moves.push({
                    oldIndex: entry.index,
                    newIndex: _newEntry.index,
                    item: entry.item
                });
        }
    });
    return {
        changes: { additions, deletions, moves },
        newKeyMap,
    };
}
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