一級Id為負數、parentId為空，二級parentId等於一級id，三級parentId等於二級id
[{"name": "廣東","Id": -1,"parentId": null} ,
{"name": "湖北","Id": -2,"parentId": null},
{"name": "廣州","Id": 44,"parentId": -1},
{"name": "武漢","Id": 58,"parentId": -2},
{"name": "深圳","Id": 12,"parentId":-1 },
{" name": "白雲","Id": 741,"parentId": 44}]
一級Id為負數、parentId為空，二級parentId等於一級id，三級parentId等於二級id
[{"name": "廣東","Id": -1,"parentId": null} ,
{"name": "湖北","Id": -2,"parentId": null},
{"name": "廣州","Id": 44,"parentId": -1},
{"name": "武漢","Id": 58,"parentId": -2},
{"name": "深圳","Id": 12,"parentId":-1 },
{" name": "白雲","Id": 741,"parentId": 44}]
<code><div id="result"></div>
<script>
var result = document.getElementById('result')
var arr = [
{"name": "广东","Id": -1,"parentId": null},
{"name": "湖北","Id": -2,"parentId": null},
{"name": "广州","Id": 44,"parentId": -1},
{"name": "武汉","Id": 58,"parentId": -2},
{"name": "深圳","Id": 12,"parentId":-1 },
{"name": "白云","Id": 741,"parentId": 44}
]
var tree = {}
var count = 0
array2Object(arr, tree, null)
function array2Object (array, node, id) {
var storage = []
var newArray = []
var newNode, newId
for (var i = 0; i < array.length; i++) {
if (array[i].parentId === id) {
node[array[i].name] = {}
storage.push(i)
count++
} else {
newArray.push(array[i])
}
}
if (count !== arr.length) {
for (var i = 0; i < storage.length; i++) {
array2Object(newArray, node[array[storage[i]].name], array[storage[i]].Id)
}
} else {
object2Html(result, tree)
}
}
function object2Html (node, obj) {
var storage = []
var tpl = node.innerHTML + '<ul>'
for (var key in obj) {
tpl = tpl + '<li data-name="' + key + '">' + key + '</li>'
if (!isEmptyObject(obj[key])) {
storage.push({
name: key,
obj: obj[key]
})
}
}
tpl += '</ul>'
node.innerHTML = tpl
if (storage.length !== 0) {
for (var i = 0; i < storage.length; i++) {
object2Html(document.querySelector('li[data-name="' + storage[i].name + '"]'), storage[i].obj)
}
}
}
function isEmptyObject (obj) {
for (var key in obj) {
return false
}
return true
}
</script></code>效果如圖
寫的有點難看，不過不受限於數組的排序（不一定要按照級數遞減），也不受限於3級。
其實這也就是一個遞歸的關係，貼下我專案中的程式碼吧：
<code> /**
* 获取树的树形的下拉列表数组
* @param string $model 模型名称
* @param int $m 点位符数量
* @param string $pid 父级id
* @param array field 字段名的数组
*/
function dropdown_tree($model,$m=0,$pid=0,$field=array('id','sortname','parentid'))
{
$model=$model."_model";
$this->_CI->load->model($model);
$class_arr=$this->_CI->$model->all();
$return_arr=array();
$this->dropdown_array($m,$pid,$class_arr,$return_arr,$field);
return $return_arr;
}
/**
* 遍历数组，修改其样式。
*/
function dropdown_array($m,$pid,$class_arr,&$return_arr,$field){
$n = str_pad('',$m,'-',STR_PAD_RIGHT);
$n = str_replace("-"," ",$n);
foreach($class_arr as $item){
if($item["$field[2]"]==$pid){
$return_arr[$item["$field[0]"]]=$n."|--".$item["$field[1]"];
$this->dropdown_array($m+1,$item["$field[0]"],$class_arr,$return_arr,$field);
}
}
}</code>
<code class="javascript"> var districts = [
{"name": "广东", "Id": 1, "parentId": 0},
{"name": "湖北", "Id": 2, "parentId": 0},
{"name": "广州", "Id": 3, "parentId": 1},
{"name": "武汉", "Id": 4, "parentId": 2},
{"name": "深圳", "Id": 5, "parentId": 0},
{"name": "白云", "Id": 6, "parentId": 3},
{"name": "江夏", "Id": 7, "parentId": 4},
{"name": "景云路", "Id": 8, "parentId": 6}
];
function arrayToTree(parentId) {
var temp = [];
for (var index in districts) {
if (districts[index].parentId == parentId) {
temp.push({
data: districts[index],
children: arrayToTree(districts[index].Id)
});
}
}
return temp;
}
function outputTree(items, depth) {
var str = '';
for (var index in items) {
/* repeat() 特性属于 ECMAScript 2015（ES6）规范 */
str += ' - - '.repeat(depth) + items[index].data.name + '<br/>';
if (items[index].children.length) {
str += outputTree(items[index].children, depth + 1);
}
}
return str;
}
var result = outputTree(arrayToTree(0), 0);
document.write(result);</code><code class="javascript">广东 - - 广州 - - - - 白云 - - - - - - 景云路 湖北 - - 武汉 - - - - 江夏 深圳</code>
PS：分隔符號可以自訂。求路過大牛幫忙最佳化：arrayToTree() ^_^
以前寫過，請直接戳這裡，懶得複製了 _^_。
非常在意性能的話這種因為數量級不大可以考慮不用3級聯動，加工一下，然後輸入如下的Option就行了。
首頁
-首頁
--首頁
首頁
就是根據ID找歸類，直接JQ判斷記載就好了
不邀自答,(考慮效能)私以為在資料根源入手是最有效直接的,來個資料庫版的.
建表語句
<code>create table TP_CITY ( Id NUMBER , name VARCHAR2(255), parentId NUMBER ); insert into tp_city values(-1,'广东', null); insert into tp_city values(-2,'湖北', null); insert into tp_city values(44,'广州', -1); insert into tp_city values(58,'武汉', -2); insert into tp_city values(12,'深圳', -1); insert into tp_city values(741,'白云', 44); </code>
例如使用oracle的層級查詢
<code>select lpad(' ', (level-1)*2, ' ')||name name
from tp_city
start with id<0 connect by parentId=prior Id;</code>回傳結果如下:
我們也可以這樣寫:
<code>select sys_connect_by_path(name, '-') path from tp_city start with id<0 connect by parentId=prior id; </code>
回傳結果是:
