const list = [{id: 100,name: 100, pid: 10}, {id: 20, name: 20, pid: 2}, {id: 1, name: 1}, {id: 2, name: 2}, {id: 10, name: 10, pid: 1}, {id: 11, name: 11, pid: 1}]

const arrayToTree = (array, pid) => {
    return array.reduce((res, current) => {
        if (current.pid === pid) {
            current.children = arrayToTree(array, current.id)
            return res.concat(current)
        }
        return res;
    }, [])
}

console.log('arrayToTree: ', arrayToTree(list))