我是 d3js 和 javascript 的新手。我正在尝试创建一个包含 8000 多个节点的树，并使用可用的基本树示例并进行修改以垂直显示。
示例数据是硬编码的，但是，在我的本地服务器上，我从外部 JSON 文件中读取数据。
我希望能够指定开始的深度级别（折叠所有深度超过 2 的节点）并允许用户进一步展开或折叠节点。
我尝试修改“折叠”功能以检查深度级别，但是逻辑不正确。
感谢这方面的任何帮助。
<!-- load the d3.js library -->
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
//------------------
var data =[{"sid":"1","parent":"null","name_ar":"Hashim"},{"sid":"2","parent":"1","name_ar":"wahb"},{"sid":"3","parent":"1","name_ar":"Abdulmuttaleb"},{"sid":"4","parent":"2","name_ar":"Amina"},{"sid":"5","parent":"3","name_ar":"Abutaleb"},{"sid":"6","parent":"3","name_ar":"Abdulla"},{"sid":"7","parent":"3","name_ar":"Abbas"},{"sid":"8","parent":"3","name_ar":"Hamza"},{"sid":"9","parent":"6","name_ar":"Mohammed (Prophet)"},{"sid":"10","parent":"9","name_ar":"Alqassim"},{"sid":"11","parent":"9","name_ar":"Um Kalthoum"},{"sid":"12","parent":"9","name_ar":"Zainab"},{"sid":"13","parent":"9","name_ar":"Ruqaya"},{"sid":"14","parent":"9","name_ar":"Fatima"},{"sid":"15","parent":"9","name_ar":"Ibrahim"},{"sid":"16","parent":"9","name_ar":"Abdulla"},{"sid":"17","parent":"9","name_ar":"Muhsen"},{"sid":"18","parent":"5","name_ar":"Ali"},{"sid":"19","parent":"18","name_ar":"Hassan"},{"sid":"20","parent":"18","name_ar":"Hussain"},{"sid":"21","parent":"20","name_ar":"Ali Zain Alabbideen"},{"sid":"22","parent":"21","name_ar":"Mohammed Baqer"},{"sid":"23","parent":"22","name_ar":"Jafar Sadeq"},{"sid":"24","parent":"23","name_ar":"Mousa Kadim"},{"sid":"25","parent":"24","name_ar":"Ali AlAreed"},{"sid":"26","parent":"24","name_ar":"Ibrahim Murtada"},{"sid":"27","parent":"26","name_ar":"Mousa (the second)"},{"sid":"28","parent":"27","name_ar":"Ahmed"},{"sid":"29","parent":"28","name_ar":"Hussain"},{"sid":"30","parent":"29","name_ar":"Abu Alqassim Mohammed"},{"sid":"31","parent":"30","name_ar":"Najm Aldeen Mahdi"}];
//need to find a way to dynamically set the "Width" as the tree is very deep
var margin = {top: 25, right: 120, bottom: 20, left: 120},
width = 10000 - margin.right - margin.left,
height = 5000 …