``` 引言 最近接手一个项目中很多地方需要用到树形结构表格等，因此自己封了个VUE的树和表格组件，需要经常对两种形式的数据进行相互转换，这里记录下转换的方法，组件等有时间再完善下也发上来。 扁平数组转换为树形结构 这个是最常用的，当我们从后台获取一个扁平数组的时候，通常比如用id、pid来标识父子关系，如： var arr = [{id: 1, pid: '-1'},{id: 11, pid: '1'},{id: 12, pid: '1'}] 用map记录的方法是最常用效果也最好的复杂度是O(nlgn),支持多个根节点: function listToTree(list) { var map = {}, node, tree= [], i; for (i = 0; i < list.length; i ++) { map[list[i].id] = list[i]; list[i].children = []; } for (i = 0; i < list.length; i += 1) { node = list[i]; if (node.pid !== '-1') { map[node.pid].children.push(node); } else { tree.push(node); } } return tree; } listToTree(arr); //[{"id":1,"pid":"-1","children":[{"id":11,"pid":"1","children":[]},{"id":12,"pid":"1","children":[]}]}] 但是项目中有个需求，在后台没有返回给带层级信息level的时候，需要用到层级信息，这样转换没法计算出层级，因此就需要用迭代的方法了，默认根节点层级为0，依次递增： function listToTreeWithLevel(list, parent, level) { var out = [] for (var node of list) { if (node.pid == parent) { node.level = level; var children = listToTreeWithLevel(list, node.id, level + 1) if (children.length) { node.children = children } out.push(node) } } return out } listToTreeWithLevel(arr, '-1', 0) //[{"id":1,"pid":"-1","children":[{"id":11,"pid":"1","children":[],"level":1},{"id":12,"pid":"1","children":[],"level":1}],"level":0}] 树形结构转换为扁平数组 这个其实就是数据结构中的广度优先遍历： function treeToList(tree) { var queen = []; var out = []; queen = queen.concat(tree); while(queen.length) { var first = queen.shift(); if (first.children) { queen = queen.concat(first.children) delete first['children']; } out.push(first); } return out; } var tree = [{"id":1,"pid":"-1","children":[{"id":11,"pid":"1","children":[]},{"id":12,"pid":"1","children":[]}]}]; treeToList(tree) //[{"id":1,"pid":"-1"},{"id":11,"pid":"1"},{"id":12,"pid":"1"}] 参考资料 listtotree 找本数据结构看看dfs和bfs ```