cvte前端最后一道建树笔试题

	
	

		let data = [
	

	

		{id: 3, val: '3', parentId: 1},
	

	

		{id: 2, val: '2', parentId: 0},
	

	

		{id: 5, val: '5', parentId: 2},
	

	

		{id: 6, val: '6', parentId: 2},
	

	

		{id: 4, val: '4', parentId: 1},
	

	

		{id: 1, val: '1', parentId: 0},
	

	

		]
	

	

		function treeish(arr, parent) {
	

	

		if(!parent) parent = {id: 0, val: '0'};
	

	

		let children = arr.filter(obj => obj.parentId === parent.id);
	

	

		children = convert(children)
	

	

		parent.children = children;
	

	

		if(children.length !== 0) {
	

	

		children.forEach(child => treeish(arr, child));
	

	

		}
	

	

		return parent;
	

	

		}
	

	

		function convert(children) {
	

	

		return children.map(child => {
	

	

		delete child.parentId;
	

	

		child.children = [];
	

	

		return child;
	

	

		});
	

	

		}
	

	

		console.info(treeish(data));