Simple Example of super-simple JS second-level and multi-level linkage

Super simple JS Code linkage, but to be used with jquery, you can also modify the code of the JS library by yourself.
Copy codeThe Code is as follows:
<Tr>
<Th> Level 1 Classification </th> <td>
<Select name = "subsidiary_cat_id" class = "subsidiary_cat_id" onchange = "linkage ('. subsidiary_cat_id', '. cat_id');">
<Option> select </option>
</Select>
<Script language = "javascript">
Var linkage_data = {$ list_file_category}; // initialize cascade data. {$ list_file_category} is the JSON_ENCODE data of PHP. The array has three pieces of data: id, parent_id, name
Function linkage (parent_dom, son_dom ){
Var parent_id = 0;
If (parent_dom ){
Parent_id = $ (parent_dom). val ();
}
$ (Son_dom). empty (); // clear the drop-down list first.
Var html = '<option> select </option> ';
$. Each (linkage_data, function (key, value ){
If (value. parent_id = parent_id ){
Html + = "<option value = '" + value. id + "'>" + value. name + "</option> ";
}
});
$ (Son_dom). append (html );
}
Linkage ('',". subsidiary_cat_id ") // if no parent node is uploaded, the first level of data is returned.
</Script>
</Td> </tr>
<Tr> <th> Level 2 Directory </th> <td>
<Select name = "cat_id" class = "cat_id">
<Option> select </option>
</Select> </td> </tr>