Select one child in EJ2 JavaScript TreeView control

28 Jan 20257 minutes to read

The TreeView control allows both single and multiple selections. If your application requires selecting one child at a time under a specific parent, refer to the following example. You can achieve this by using the nodeSelecting event in the TreeView control. However, you can reset the selected child and make another selection by pressing Ctrl + selected nodes.

/**
* Single child selection
*/

// Hierarchical data source for TreeView control
var localData = [
  { id: 1, name: 'Parent 1', hasChild: true, expanded: true },
  { id: 2, pid: 1, name: 'Child 1' },
  { id: 3, pid: 1, name: 'Child 2' },
  { id: 4, pid: 1, name: 'Child 3' },
  { id: 7, name: 'Parent 2', hasChild: true, expanded: true },
  { id: 8, pid: 7, name: 'Child 1' },
  { id: 9, pid: 7, name: 'Child 2' },
  { id: 10, pid: 7, name: 'Child 3' },
];
var tree1 = new ej.navigations.TreeView({
  fields: { dataSource: localData, id: 'id', text: 'name', parentID: 'pid', hasChildren: 'hasChild' },
  loadOnDemand: false,
  allowMultiSelection: true,
  nodeSelecting: onNodeSelecting
});
tree1.appendTo('#tree');

var parent, child;
var count = false;
var childCount = false;

function onNodeSelecting(args) {
  var id = args.nodeData.parentID;
  if (!count) {
    parent = id;
    count = true;
  }
  if (!childCount) {
    child = args.nodeData.id;
    childCount = true
  }
  if (id != null && id === parent) {
    var element = tree1.element.querySelector('[data-uid="' + id + '"]');
    var liElements = element.querySelectorAll('ul li');
    for (var i = 0; i < liElements.length; i++) {
      var nodeData = tree1.getNode(liElements[i]);
      if (nodeData.selected && args.action === "select" && child !== args.nodeData.id) {
        args.cancel = true;
      }
      // For unselect the selectedNodes
      else if (args.action === "un-select" && child === args.nodeData.id) {
        childCount = false;
        child = null;
        parent = null;
        count = false;
      }
    }
  } else if (id !== parent && id !== null) {
    if (args.action == "select") {
      args.cancel = true
    }
  } else if (id === null) {
    childCount = false;
    child = null;
    parent = null;
    count = false
  }
}
<!DOCTYPE html>
<html lang="en">

<head>
  <title>Essential JS 2 for TreeView </title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="description" content="Essential JS 2 for TreeView UI Control">
  <meta name="author" content="Syncfusion">
  <link href="index.css" rel="stylesheet">
  <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
  <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-inputs/styles/material.css" rel="stylesheet">
  <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-navigations/styles/material.css" rel="stylesheet">
  <script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
  <div id="container">
    <div id="treeparent">
      <div id="tree"></div>
    </div>
  </div>

  <script>
    var ele = document.getElementById('container');
    if (ele) {
      ele.style.visibility = "visible";
    }   
  </script>
  <script src="index.js" type="text/javascript"></script>
  <style>
    #treeparent {
      display: block;
      max-width: 350px;
      max-height: 350px;
      margin: auto;
      overflow: auto;
      border: 1px solid #dddddd;
      border-radius: 3px;
    }
  </style>
</body>

</html>
#container {
  visibility: hidden;
}

#loader {
  color: #008cff;
  height: 40px;
  width: 30%;
  position: absolute;
  font-family: 'Helvetica Neue', 'calibiri';
  font-size: 14px;
  top: 45%;
  left: 45%;
}