普通分类变树形分类的原理
普通分类变树形分类原理
知识点：递归
说明.
数据从数据库取出来就是下述一条一条的没有父子嵌套
因此如果需要嵌套
方案1：直接请求树形控件，原因：后端拿到数据库后递归好了再返回
方案2：请求接口拿到数据库后，用下述方法递归过滤数据
<script>
let arr = [
{cat_id:1, name: '零食', pid: 0, level: 1},
{cat_id:2, name: '生活用品', pid: 0, level: 1},
{cat_id:3, name: '攻城狮', pid: 0, level: 1},
{cat_id:4, name: '方便面', pid: 1, level: 2},
{cat_id:5, name: '汽水', pid: 1, level: 2},
{cat_id:6, name: '薯条', pid: 1, level: 2},
{cat_id:7, name: '床单', pid: 2, level: 2},
{cat_id:8, name: '枕头', pid: 2, level: 2},
{cat_id:9, name: '洗发水', pid: 2, level: 2},
{cat_id:10, name: 'WEB大前端', pid: 3, level: 2},
{cat_id:11, name: 'JAVA', pid: 3, level: 2},
{cat_id:12, name: 'PYTHON', pid: 3, level: 2},
{cat_id:13, name: 'JS变量', pid: 10, level: 3},
{cat_id:14, name: 'JS判断', pid: 10, level: 3},
{cat_id:15, name: 'JS循环', pid: 10, level: 3},
{cat_id:16, name: 'JAVA变量', pid: 11, level: 3},
{cat_id:17, name: 'JAVA判断', pid: 11, level: 3},
{cat_id:18, name: 'JAVA循环', pid: 11, level: 3},
]
function findById (cat_id)
{
let child = [];
arr.forEach((value) => {
if (value.pid == cat_id) {
child.push(value);
}
});
return child;
}
function getTree(cat_id = 0)
{
let dataArr = findById(cat_id);
if (dataArr.length <= 0) {
return null;
} else {
dataArr.forEach((value) => {
if (getTree(value.cat_id) != null) {
value["children"] = getTree(value.cat_id);
}
});
}
return dataArr;
}
console.log(getTree());
</script>