json内容格式的转换，目的是为了使用el的树图组件
```javascript
[
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 1,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 2
}],
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 2,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 2
}]
]
root可以不用管, R = 0 属于一级节点 R > 0 且RR = -1 或0属于二级节点 R > 0 且RR > 0 属于三级节点
我想用el的组件， 需要变换json的内容形式， 但每次到了三级节点就会出错
前端刚接触不久， 我也只会用笨办法， 遍历 + 判断得到一级节点， 再再其中遍历 + 判断……
避免贻笑大方， 代码我就不贴出来了， 这个问题困扰了我四天了， 尝试了五六次都不行,
希望解决方法不要依靠label或者valuee的值
诉求是上面的形式变成下边这样的：
```javascript
[{
id: 1,
label: 'a:123',
children: [{
id: 3,
label: 'b123',
children: [{
id: 5,
label: 'c123',
}, {
id: 6,
label: 'd123',
}]
}]
}, {
id: 2,
label: 'a:123',
children: [{
id: 4,
label: 'b123',
children: [{
id: 7,
label: 'c123',
}, {
id: 8,
label: 'd123',
}]
}]
}]
希望能给出可以使用的代码，如果应用时遇到问题，我会继续追问到可以正常使用为止。
我不会问该问题应用范围外的问题，请放心。
哈喽，代码大概是这样，一次遍历存长度，为了设置id，二次遍历设置数据：有用请点采纳哦~
const arr = [
[
{
label: "a",
selectt: [
{
valuee: "123",
},
],
root: 1,
R: 0,
RR: -1,
},
{
label: "b",
selectt: [
{
valuee: "123",
},
],
root: 1,
R: 1,
RR: 0,
},
{
label: "c",
selectt: [
{
valuee: "123",
},
],
root: 1,
R: 1,
RR: 1,
},
{
label: "d",
selectt: [
{
valuee: "123",
},
],
root: 1,
R: 1,
RR: 2,
},
],
[
{
label: "a",
selectt: [
{
valuee: "123",
},
],
root: 2,
R: 0,
RR: -1,
},
{
label: "b",
selectt: [
{
valuee: "123",
},
],
root: 2,
R: 1,
RR: 0,
},
{
label: "c",
selectt: [
{
valuee: "123",
},
],
root: 2,
R: 1,
RR: 1,
},
{
label: "d",
selectt: [
{
valuee: "123",
},
],
root: 2,
R: 1,
RR: 2,
},
],
];
const res = []; // 结果
const len = [0, 0]; // 存长度，第一个为二级长度，第二个为三级长度
arr.forEach(out => {
out.forEach(v => {
if (v.R > 0) {
v.RR <= 0?len[0]++:len[1]++;
}
});
});
const index = [0, 0]; // 存下标，第一个为二级下标，第二个为三级下标
arr.forEach((out, i) => {
res.push({
id: i + 1,
children: [],
});
out.forEach((v) => {
const sel = v.selectt.map((v) => v.valuee).join(","); // valuee转字符串
const label = `${v.label}:${sel}`; // 拼接label
if (v.R == 0) {
// 一级
res[i].label = label;
} else if (v.R > 0) {
if (v.RR <= 0) {
// 二级
res[i].children.push({
id: arr.length + index[0] + 1,
label,
children: [],
});
index[0]++;
} else {
// 三级
res[i].children[v.R - 1].children.push({
id: arr.length + len[0] + index[1] + 1,
label,
children: [],
});
index[1]++;
}
}
});
});
console.log(res)
大概写了个，结构是满足了，不知道是否还有其他的要求，特别是二级节点只有1个？多个的话从原始数据看不出2级和3级的对应关系
<script>
var data =
[
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 1,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 2
}],
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 2,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 2
}]
];
var newdata = [];
data.forEach(item => {
var root = item.find(i => i.R == 0);
var nitem = { label: root.label + ':' + root.selectt[0].valuee, children: [] }
var secitem = item.find(i => i.R > 0 && (i.RR == -1 || i.RR == 0));
var nsecitem = { label: secitem.label + ':' + secitem.selectt[0].valuee, children: [] };
nitem.children.push(nsecitem);
item.filter(i => i.R > 0 && i.RR > 0).forEach(thirditem => {
nsecitem.children.push({ label: thirditem.label + ':' + thirditem.selectt[0].valuee });
});
newdata.push(nitem);
});
var id = 1;
newdata.forEach(item => {
item.id = id++;
});
newdata.forEach(item => {
item.children.forEach(item => { item.id = id++; })
});
newdata.forEach(item => {
item.children.forEach(item => {
item.children.forEach(item => { item.id = id++ });
})
});
console.log(JSON.stringify(newdata,null,2))
</script>
let data = [
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 1,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 1,
R: 1,
RR: 2
}],
[{
label: 'a',
selectt: [{
valuee: '123'
}],
root: 2,
R: 0,
RR: -1
}, {
label: 'b',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 0
}, {
label: 'c',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 1
}, {
label: 'd',
selectt: [{
valuee: '123'
}],
root: 2,
R: 1,
RR: 2
}]
];
//扁平化
let data1 = data.flat();
data1.forEach(v=>{
if(!result[`root_${v.root}`]){
result[`root_${v.root}`]={l1:[],l2:[],l3:[]};
};
if(v.R===0){
result[`root_${v.root}`].l1.push({id:v.root,label:`${v.label}:${v.selectt[0].valuee}`});
}
if(v.R>0&&(v.RR<=0)){
result[`root_${v.root}`].l2.push({id:v.root,label:`${v.label}:${v.selectt[0].valuee}`});
}
if(v.R>0&&(v.RR>0)){
result[`root_${v.root}`].l3.push({id:v.root,label:`${v.label}:${v.selectt[0].valuee}`});
}
});
let final=[];//这个就是最后的结果
Object.keys(result).forEach(v=>{let temp = {id:result[v].l1[0].id,label:result[v].l1[0].label,children:result[v].l2}; temp.children.children=result[v].l3; final.push(temp)});
console.log(final);//打印一下结果
这个转换应该是在后台实现更好哦，使用JSONObject,JSONArray对象嵌套实现。