Context menu for Angular

A context menu component for Angular.

Plans

• ✔️ Fork the project from an unmaintained repository
• ✔️ Support Angular 12 and the following releases
• 📈 Increase the code coverage to have a better deep understanding of the code base
  • the original repo had no tests at all and now
• Cleanup and reduce the public API as well as properly document it
• Provide better demo

Installation

• Installation command

npm install @perfectmemory/ngx-contextmenu @angular/cdk

yarn add @perfectmemory/ngx-contextmenu @angular/cdk

• Import in your Angular main module

import { ContextMenuModule } from '@perfectmemory/ngx-contextmenu';
@NgModule({
  ...
  imports: [
    ContextMenuModule.forRoot({
      autoFocus: true,
    }),
  ],
  ...
})
export class AppModule {}

• Import Angular CDK prebuilt in your styles

@import '@angular/cdk/overlay-prebuilt.css';

Angular compatibility

Usage

Template

<ul>
  <li
    *ngFor="let item of items"
    [contextMenu]="basicMenu"
    [contextMenuSubject]="item"
  >
    Right Click: {{ item?.name }}
  </li>
</ul>

<context-menu #basicMenu>
  <ng-template
    contextMenuItem
    (execute)="showMessage(`Hi, ${$event.item.name}`)"
  >
    Say hi!
  </ng-template>
  <ng-template contextMenuItem divider="true"></ng-template>
  <ng-template
    contextMenuItem
    let-item
    (execute)="showMessage(`${$event.item.name} said: ${$event.item.otherProperty}`)"
  >
    Bye, {{ item?.name }}
  </ng-template>
  <ng-template contextMenuItem passive="true">
    Input something: <input type="text" />
  </ng-template>
</context-menu>

Component Code

@Component({
  ...
})
export class Component {
  public items = [
    { name: 'John', otherProperty: 'Foo' },
    { name: 'Joe', otherProperty: 'Bar' }
  ];

  @ViewChild(ContextMenuComponent)
  public basicMenu: ContextMenuComponent;

  public showMessage(message: string) {
    console.log(message);
  }
}

Context Menu Items

• A line of context menu is a <ng-template> element with a contextMenuItem attribute directive and following optional inputs
  • divider (boolean) (default=false) when true all the other inputs are ignored, the item is a simple divider without action
  • passive (boolean) (default=false) when true the menu item will not emit execute events or close the context menu when clicked.
  • enabled (boolean | item => boolean) (default=true) Can be a boolean value or a function that takes an item and returns a boolean.
  • visible (boolean | item => boolean) (default=true) Can be a boolean value or a function that takes an item and returns a boolean.

<ng-template
  contextMenuItem
  [divider]="true/false"
  [enabled]="true/false"
  [passive]="true/false"
  [visible]="true/false"
  (execute)="method($event)"
></ng-template>

• Use template binding let-item to reference the item object inside the menu item template

Note: Make sure to use optional chaining when accessing item properties item?.name as the item will be initially undefined

<ng-template
  contextMenuItem
  let-item
  (execute)="showMessage(`${$event.item.name} said: ${$event.item.otherProperty}`)"
>
  {{ item?.name }}
</ng-template>

• Menu items emit on execute output. The $event object is of the following form

{ event: MouseEvent, item: any }

Sub menus

You can specify sub menus like this:

<ul>
  <li
    *ngFor="let item of items"
    [contextMenu]="basicMenu"
    [contextMenuSubject]="item"
  >
    Right Click: {{item?.name}}
  </li>
</ul>
<context-menu #basicMenu>
  <ng-template contextMenuItem [subMenu]="saySubMenu"> Say... </ng-template>
  <context-menu #saySubMenu>
    <ng-template
      contextMenuItem
      (execute)="showMessage(`Hi, ${$event.item.name}`)"
    >
      ...hi!
    </ng-template>
    <ng-template
      contextMenuItem
      (execute)="showMessage(`Hola, ${$event.item.name}`)"
    >
      ...hola!
    </ng-template>
    <ng-template
      contextMenuItem
      (execute)="showMessage(`Salut, ${$event.item.name}`)"
    >
      ...salut!
    </ng-template>
  </context-menu>
  <ng-template contextMenuItem divider="true"></ng-template>
  <ng-template
    contextMenuItem
    let-item
    (execute)="showMessage(`${$event.item.name} said: ${$event.item.otherProperty}`)"
  >
    Bye, {{item?.name}}
  </ng-template>
  <ng-template contextMenuItem passive="true">
    Input something: <input type="text" />
  </ng-template>
</context-menu>

Notes:

1. Sub <context-menu> cannot be placed inside the <ng-template> that references it
2. Sub-menus may be nested as deeply as you wish.

Using visible and enabled functions

If you need access to properties in your component from within the enabled or visible functions, you can pass in an arrow function.

<ng-template ... [visible]="isMenuItemOutsideValue"></ng-template>

public outsideValue = "something";

public isMenuItemOutsideValue = (item: any): boolean => {
  return item.type === this.outsideValue;
}

Multiple Context Menus

You can use multiple context menus in the same component if you would like.

<ul>
  <li
    *ngFor="let item of items"
    [contextMenu]="basicMenu"
    [contextMenuSubject]="item"
  >
    {{item?.name}}
  </li>
</ul>
<context-menu #basicMenu> ... </context-menu>

<ul>
  <li
    *ngFor="let item of items"
    [contextMenu]="otherMenu"
    [contextMenuSubject]="item"
  >
    {{ item?.name }}
  </li>
</ul>
<context-menu #otherMenu> ... </context-menu>

@ViewChild('basicMenu')
public basicMenu: ContextMenuComponent;

@ViewChild('otherMenu')
public otherMenu: ContextMenuComponent;

Other use cases

Context menu in a different component

If your <context-menu> component is in a different component from your list, you'll need to wire up the context menu event yourself.

<ul>
  <li *ngFor="let item of items" (contextmenu)="onContextMenu($event, item)">
    Right Click: {{item.name}}
  </li>
</ul>

import { ContextMenuService } from '@perfectmemory/ngx-contextmenu';

@Component({
  ...
})
export class MyContextMenuClass {
  public items = [
    { name: 'John', otherProperty: 'Foo' },
    { name: 'Joe', otherProperty: 'Bar' }
  ];

  // Optional
  @Input()
  public contextMenu: ContextMenuComponent;

  constructor(private contextMenuService: ContextMenuService) {}

  public onContextMenu(event: MouseEvent, item: any): void {
    this.contextMenuService.show.next({
      // Optional - if unspecified, all context menu components will open
      contextMenu: this.contextMenu,
      event,
      item: item,
    });
    event.preventDefault();
    event.stopPropagation();
  }
}

Triggering the context menu with a different Event

The context menu can be triggered at any point using the method above. For instance, to trigger the context menu with a left click instead of a right click, use this html:

<ul>
  <li *ngFor="let item of items" (click)="onContextMenu($event, item)">
    Left Click: {{item.name}}
  </li>
</ul>

This could be (keydown), (mouseover), or (myCustomEvent) as well.

Positioning the context menu around an element

If you want to override the context menu positioning to be appended to an element instead of based on mouse position, provide an anchorElement to the contextMenuService. This makes sense if you want to trigger the context menu with a non-MouseEvent.

public onContextMenu(event: KeyboardEvent, item: any): void {
  this.contextMenuService.show.next({
    anchorElement: event.target,
    // Optional - if unspecified, all context menu components will open
    contextMenu: this.contextMenu,
    event: <any>event,
    item: item,
  });
  event.preventDefault();
  event.stopPropagation();
}

Custom Styles

The html that is generated for the context menu looks like this:

<div class="dropdown ngx-contextmenu">
  <ul class="dropdown-menu">
    <li>
      <a><!-- the template for each context menu item goes here --></a>
      <span
        ><!-- the template for each passive context menu item goes here --></span
      >
    </li>
  </ul>
</div>

You can key off of the ngx-contextmenu class to create your own styles. Note that the ul.dropdown-menu will have inline styles applied for position, display, left and top so that it will be positioned at the cursor when you right-click.

.ngx-contextmenu .dropdown-menu {
  border: solid 1px chartreuse;
  background-color: darkgreen;
  padding: 0;
}
.ngx-contextmenu li {
  display: block;
  border-top: solid 1px chartreuse;
  text-transform: uppercase;
  text-align: center;
}
.ngx-contextmenu li:first-child {
  border-top: none;
}
.ngx-contextmenu a {
  color: chartreuse;
  display: block;
  padding: 0.5em 1em;
}
.ngx-contextmenu a:hover {
  color: darkgreen;
  background-color: chartreuse;
}

Bootstrap 4

If you're using Bootstrap 4, you can specify a useBootstrap4 property in the forRoot function of the ContextMenuModule in order to get the appropriate class names. Like this:

@NgModule({
  import: [
    ContextMenuModule.forRoot({
      useBootstrap4: true,
    }),
  ],
})
export class AppModule {}

Or, if you want to repeat yourself, you can add a useBootstrap4 attribute to each context-menu component. Like this:

<context-menu [useBootstrap4]="true"></context-menu>

Different styling on menus

If you want to style one menu differently than other menus, you can add a custom style to the menu.

<context-menu menuClass="custom-class"></context-menu>

Please note that the style needs to be global to affect the menu, since the menu element is added to the page outside the component that triggers the menu.

AutoFocus

You can optionally set focus on the context menu whenever it opens. This enables a user to easily tab through the context menu items and press enter to select them.

@NgModule({
  import: [
    ContextMenuModule.forRoot({
      autoFocus: true,
    }),
  ],
})
export class AppModule {}

Keyboard navigation

You can use the keyboard to manipulate the context menu. Note: Keyboard navigation should be used in conjunction with autoFocus, since key events are only captured when the context menu is focused.

Disable Context Menu

If you need to disable the context menu, you can pass a boolean to the [disabled] input:

<context-menu [disabled]="true"></context-menu>

Close event emitter

There is a (close) output EventEmitter that you can subscribe to for notifications when the context menu closes (either by clicking outside or choosing a menu item).

<context-menu (close)="processContextMenuCloseEvent()"></context-menu>

Dynamic context menu

The items in the context menu are completely controlled by the contextMenuActions object.

<ul>
  <li
    *ngFor="item in items"
    [contextMenu]="myContextMenu"
    [contextMenuSubject]="item"
  >
    Right Click: {{item.name}}
  </li>
</ul>
<context-menu #myContextMenu>
  <ng-template
    *ngFor="let action of contextMenuActions"
    contextMenuItem
    let-item
    [visible]="action.visible"
    [enabled]="action.enabled"
    [divider]="action.divider"
    (execute)="action.click($event.item)"
  >
    {{ action.html($event.item) }}
  </ng-template>
</context-menu>

@Component({
  ...
})
export class Component {
  @ViewChild(ContextMenuComponent)
  public contextMenu: ContextMenuComponent;

  public items = [
    { name: 'John', otherProperty: 'Foo', type: 'type1' },
    { name: 'Joe', otherProperty: 'Bar', type: 'type2' }
  ];
  public contextMenuActions = [
    {
      html: (item) => `Say hi!`,
      click: (item) => alert('Hi, ' + item.name),
      enabled: (item) => true,
      visible: (item) => item.type === 'type1',
    },
    {
      divider: true,
      visible: true,
    },
    {
      html: (item) => `Something else`,
      click: (item) => alert('Or not...'),
      enabled: (item) => false,
      visible: (item) => item.type === 'type1',
    },
  ];
}

Inspiration and previous work

This project has been initially forked from ngx-contextmenu to make it possible to port it to Angular 13. It was originally inspired by ui.bootstrap.contextMenu.