const data = [
{ id: 1, name:'parent1',parent:0},
{ id: 2, name:'child1',parent:1},
{ id: 3, name:'child2',parent:1},
{ id: 4, name:'parent2',parent:0},
{ id: 5, name:'child3',parent:4},
{ id: 6, name:'child4',parent:4},
]
<ul>
<li>
parent1
<ul>
<li>child1</li>
<li>child2</li>
</ul>
</li>
<li>
parent2
<ul>
<li>child3</li>
<li>child4</li>
</ul>
</li>
</ul>