jora-tree.js

methods = {
    tree_: function(current, getter, rootValue, makeLeaf = (item, children) => ({ item, children })) {
        const scan = new Set(ensureArray(current));
        const hasParent = new Set();
        const leafs = new Map();
        const fn = typeof getter === 'function'
            ? getter
            : current => getPropertyValue(current, getter);
        const isRootValue = typeof rootValue === 'function'
            ? rootValue
            : rootValue === undefined
                ? value => value === undefined || value === null
                : value => value === rootValue;
        const vis = new Set();
        const makeLeafs = item => {
            if (vis.has(item)) { console.log('!!!', item); return; }
            vis.add(item);
            return makeLeaf(item, leafs.has(item) ? leafs.get(item).map(makeLeafs) : null);
        };

        // resolving
        scan.forEach(item => {
            const parent = fn(item);

            if (leafs.has(parent)) {
                leafs.get(parent).push(item);
            } else {
                leafs.set(parent, [item]);
            }

            if (parent !== item) {
                hasParent.add(item);
                if (!isRootValue(parent)) {
                    scan.add(parent);
                }
            }
        });

        // assembly
        return [...leafs.keys()].filter(k => !hasParent.has(k)).map(makeLeafs);
    }
}