Customize the expand and collapse icons in Angular TreeView component

7 Jan 202514 minutes to read

You can customize the TreeView expand and collapse icons by using the cssClass property of TreeView.

Refer to the sample below to see how to customize expand/collapse icons

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { TreeViewModule } from '@syncfusion/ej2-angular-navigations'
import { Component, ViewChild } from '@angular/core';
import { TreeViewComponent } from '@syncfusion/ej2-angular-navigations';

@Component({
    imports: [
        FormsModule, TreeViewModule
    ],
    standalone: true,
    selector: 'app-container',
    // specifies the template string for the TreeView component
    template: `<div id='treeparent'><ejs-treeview id='treeelement' [fields]='field' [cssClass]='cssClass'></ejs-treeview></div>`
})
export class AppComponent {
    @ViewChild('samples')
    public tree?: TreeViewComponent;

    constructor() {
    }
    // defined the array of data
    public hierarchicalData: Object[] = [
        {
            id: '01', name: 'Local Disk(C:)', expanded: true,
            subChild: [
                {
                    id: '01-01', name: 'Program Files',
                    subChild: [
                        { id: '01-01-01', name: '7-Zip' },
                        { id: '01-01-02', name: 'Git' },
                        { id: '01-01-03', name: 'IIS Express' },
                    ]
                },
                {
                    id: '01-02', name: 'Users', expanded: true,
                    subChild: [
                        { id: '01-02-01', name: 'Smith' },
                        { id: '01-02-02', name: 'Public' },
                        { id: '01-02-03', name: 'Admin' },
                    ]
                },
                {
                    id: '01-03', name: 'Windows',
                    subChild: [
                        { id: '01-03-01', name: 'Boot' },
                        { id: '01-03-02', name: 'FileManager' },
                        { id: '01-03-03', name: 'System32' },
                    ]
                },
            ]
        },
        {
            id: '02', name: 'Local Disk(D:)',
            subChild: [
                {
                    id: '02-01', name: 'Personals',
                    subChild: [
                        { id: '02-01-01', name: 'My photo.png' },
                        { id: '02-01-02', name: 'Rental document.docx' },
                        { id: '02-01-03', name: 'Pay slip.pdf' },
                    ]
                },
                {
                    id: '02-02', name: 'Projects',
                    subChild: [
                        { id: '02-02-01', name: 'ASP Application' },
                        { id: '02-02-02', name: 'TypeScript Application' },
                        { id: '02-02-03', name: 'React Application' },
                    ]
                },
                {
                    id: '02-03', name: 'Office',
                    subChild: [
                        { id: '02-03-01', name: 'Work details.docx' },
                        { id: '02-03-02', name: 'Weekly report.docx' },
                        { id: '02-03-03', name: 'Wish list.csv' },
                    ]
                },
            ]
        },
        {
            id: '03', name: 'Local Disk(E:)', icon: 'folder',
            subChild: [
                {
                    id: '03-01', name: 'Pictures',
                    subChild: [
                        { id: '03-01-01', name: 'Wind.jpg' },
                        { id: '03-01-02', name: 'Stone.jpg' },
                        { id: '03-01-03', name: 'Home.jpg' },
                    ]
                },
                {
                    id: '03-02', name: 'Documents',
                    subChild: [
                        { id: '03-02-01', name: 'Environment Pollution.docx' },
                        { id: '03-02-02', name: 'Global Warming.ppt' },
                        { id: '03-02-03', name: 'Social Network.pdf' },
                    ]
                },
                {
                    id: '03-03', name: 'Study Materials',
                    subChild: [
                        { id: '03-03-01', name: 'UI-Guide.pdf' },
                        { id: '03-03-02', name: 'Tutorials.zip' },
                        { id: '03-03-03', name: 'TypeScript.7z' },
                    ]
                },
            ]
        }
    ];
    // maps the appropriate column to fields property
    public field: Object = { dataSource: this.hierarchicalData, id: 'id', text: 'name', child: 'subChild' };
    // set the Multi Selection option to TreeView
    public cssClass: string = "custom";
}
@import 'node_modules/@syncfusion/ej2-base/styles/material.css';
@import 'node_modules/@syncfusion/ej2-inputs/styles/material.css';
@import 'node_modules/@syncfusion/ej2-buttons/styles/material.css';
@import 'node_modules/@syncfusion/ej2-angular-base/styles/material.css';
@import 'node_modules/@syncfusion/ej2-angular-navigations/styles/material.css';
@import 'node_modules/@syncfusion/ej2-angular-inputs/styles/material.css';

.custom .e-list-item .e-icons {
    font-family: "Customize-icon";
  }
  
.custom.e-treeview .e-list-item div.e-icons.e-icon-expandable::before,
.custom.e-treeview .e-list-item div.e-icons.e-icon-collapsible::before {
  content: '\e700';
  font-size: 12px;
}
  
  @font-face {
    font-family: 'Customize-icon';
    src: url(data:application/x-font-ttf;charset=utf-8;base64,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) format('truetype');
    font-weight: normal;
    font-style: normal;
  }
  

#treeparent {
    display: block;
    max-width: 400px;
    max-height: 330px;
    margin: auto;
    overflow: auto;
    border: 1px solid #dddddd;
    border-radius: 3px;
}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));