SOURCE

const data = {
	name: 'all',
	children: [
		{
			name: '图片',
			children: [
				{
					name: 'image1.jpg'
				},
				{
					name: '风景',
					children: [
						{
							name: 'guilin.jpg'
						},
						{
							name: 'hainan.jpg'
						}
					]
				},
				{
					name: 'image2.jpg'
				}
			],
		},
		{
			name: '视频',
			children: [
				{
					name: 'video1.mp4'
				},
				{
					name: 'video2.mp4'
				}
			]
		},
		{
			name: '文档',
			children: [
				{
					name: 'document1.doc'
				},
				{
					name: '小说',
					children: [
						{
							name: 'novel.txt'
						},
						{
							name: 'novel2.txt'
						}
					]
				},
				{
					name: 'document2.doc'
				}
			]
		}
	]
}
const bfs = (tree, ope) => {
	const walk = (tree, depth = 1) => {
		const queue = []
		ope(tree.name, depth)
		if(tree.children){
			queue.push({
				nodes: tree.children,
				depth: depth + 1
			})
		}
		while(queue.length) {
			const item = queue.pop()
			item.nodes && item.nodes.forEach(node => {
				ope(node.name, item.depth)
				if(node.children) {
					queue.push({
						nodes: node.children,
						depth: item.depth + 1
					})
				}
			})
		}
	}
	walk(tree)
}
bfs(data,(name, depth) => {
	let pre = '';
	for(let i =0; i < depth; i++) {
		pre += '--'
	}
	document.write(pre + name + '<br>')
})