javascript 无限分类

/**
 * 根节点 parentid=0, 每个节点都有id, parentid字段
 * @param items
 * @returns {*}
 */
function getTree(items) {
    "use strict";
    var children = new Map();
    items.forEach(function(item){
        if (children.has(item.parentid)) {
            children.get(item.parentid).push(item);
        } else {
            children.set(item.parentid, [item]);
        }
    });
    items.forEach(function(item) {
        if (children.has(item.id)) {
            item.children = children.get(item.id);
        }
    });
    return children.get(0);
}

var items = [{
    "id": 4,
    "parentid": 2,
    "name": "Laravel"
}, {
    "id": 1,
    "parentid": 0,
    "name": "PHP"
}, {
    "id": 43,
    "parentid": 42,
    "name": "PHPStorm"
}, {
    "id": 44,
    "parentid": 42,
    "name": "EclipsePDT"
}, {
    "id": 2,
    "parentid": 1,
    "name": "PHP_Framework"
}, {
    "id": 3,
    "parentid": 2,
    "name": "ThinkPHP5"
}, {
    "id": 42,
    "parentid": 1,
    "name": "DevTools"
}];

var c = getTree(items);
// console.log(c);
console.log(JSON.stringify(c));