ngx-drag-to-select

A lightweight, fast, configurable and reactive drag-to-select component for Angular 6 and beyond

⚠️ If your application does not use Angular >= v13.x then please use ngx-drag-to-select@4.x. Version 5 only supports the new package format which removes ViewEngine specific metadata. For more information check out the FAQ.

Demo

Live Demo

Playground

In case you want to take it for a test drive, check out this StackBlitz ⚡️.

Features

• Drag to Select
• Shortcuts
• Customizable 💅
• Lightweight
• Easy to use
• Ready for AoT and SSR
• Complies with the Angular Package Format
• Includes FESM2015, FESM5, and UMD bundles 📦
• It's fast 🏎
• Mobile friendly 📱
• Thoroughly tested 🚨

Examples

• Desktop Example: Check out the AppComponent!
• Mobile Example: There's a dedicated PhoneComponent component that uses all the tools and features from this library to implement a Google Inbox-like selection experience.

Table of contents

• Installation
• Setup
• Usage
• Configuration Options
• API
• FAQ
• Want to contribute?
• For developers
• Versioning
• Licence

Installation

npm install ngx-drag-to-select

or

yarn add ngx-drag-to-select

The above will install the latest stable version. If you wish to live on the edge you can also use the next tag. Doing so gives you the latest alpha, beta or release candidate.

Setup

Setting up ngx-drag-to-select is easy, and it only takes a few steps!

Adding the CSS

The first step is to add the CSS and for that you have two options. Either you use the default styles or you can import the ngx-drag-to-select sass package directly. The latter gives you the option to override variables and customize for instance the look and feel of the selection rectangle.

Using the default styles

Copy ngx-drag-to-select.css to your project and add it as a style tag to your index.html.

It's not recommended, and not supported, to load the CSS in your SCSS files. Instead, if you don't need to customize the styles, and you're using the Angular CLI you can add it to your angular.json:

"styles": [
  "src/styles.scss",
+ "node_modules/ngx-drag-to-select/ngx-drag-to-select.css"
]

Using Sass

If you're using Sass you can simply import ngx-drag-to-select into src/styles.scss. This allows you to override the default variables to customize the library to your needs.

@import 'ngx-drag-to-select';

Adding the module

In your AppModule import DragToSelectModule from ngx-drag-to-select and add it to the module imports:

import { value DragToSelectModule } from 'ngx-drag-to-select';

@NgModule({
  imports: [DragToSelectModule.forRoot()],
})
export class AppModule {}

That's it. You are now ready to use this library in your project. Make sure to call forRoot() only once in your AppModule and for feature modules you simply add the DragToSelectModule as is without calling forRoot().

Usage

Once you have installed the library and added the DragToSelectModule to your application you are ready to go.

Anywhere in your template add the dts-select-container component and wrap all items that you want to be selectable in this component.

Next, mark all selectable items with the dtsSelectItem directive. This connects each item with the container component.

Here's a complete example:

<dts-select-container
  #container="dts-select-container"
  [(selectedItems)]="selectedDocuments"
  (select)="someMethod($event)"
>
  <ul>
    <li [dtsSelectItem]="document" *ngFor="let document of documents">{{ document.name }}</li>
  </ul>
</dts-select-container>

Configuration Options

This section gives you an overview of things you can customize and configure.

Overriding sass variables

You can override the following variables:

Variable	Type	Default	Description
$dts-primary	Color	#7ddafc	Primary color
$select-box-color	Color	$dts-primary	Color of the selection rectangle
$select-box-removing-color	Color	$dts-primary	Color of the selection rectangle when removing items
$select-box-border-size	Unit	2px	Border size for the selection rectangle
$selected-item-border	Boolean	true	Whether the selected item should get a border
$selected-item-border-color	Color	#d2d2d2	Border color of the selected item
$selected-item-border-size	Unit	1px	Border size of the selected item
$box-shadow	Boolean	true	Whether the selected item should get a box shadow
$range-start-border	Boolean	true	Whether the range start item is highlighted with a border
$range-start-border-color	Color	#2196f3	Border color of the range start item

If you wish to override one of these variables, make sure to do that before you import the sass package.

Example:

// Example for overriding the color of the selection retangle
$select-box-color: red;

@import '~ngx-drag-to-select/scss/ngx-drag-to-select';

Keep in mind that default styles are applied to all drag-to-select instances in your application. This means that if you override the color of the select box and set it so something like red then all instances render a red selection rectangle.

Configuring DragToSelectModule

This library allows to you override certain options, such as

selectedClass (String)

Class that is added to an item when it's selected. The default class is selected. Note that if you override this option, you'll lose the default styling and must take care of this yourself.

shortcuts (Object)

ngx-drag-to-select supports a hand full of shortcuts to make our live easier when selecting items.

Shortcut	Default	Description
moveRangeStart	shift + r	Move range start without selecting the item
disableSelection	alt	Disable selection mode to allow selecting text on the screen within the drag area
toggleSingleItem	meta	Add or remove single item to / from selection
addToSelection	shift	Range selection, Add items to selection
removeFromSelection	shift + meta	Remove items from selection

You can override these options by passing a configuration object to forRoot().

Here's an example:

import { value DragToSelectModule } from 'ngx-drag-to-select';

@NgModule({
  imports: [
    DragToSelectModule.forRoot({
      selectedClass: 'my-selected-item',
      shortcuts: {
        disableSelection: 'alt+meta,d',
      },
    }),
  ],
})
export class AppModule {}

This will override the disableSelection with two possible shortcuts, either alt + meta or just d. If you want to learn more about shortcut alternatives, check this section.

Note: If you override one of the shortcuts you have to make sure they do not interfear with one another to ensure a smooth selecting experience.

Modifiers

When overriding the default shortcuts you can use the following modifier keys:

shift alt ctrl meta

Or you can use any key from a - z.

When using meta, it will be substituted with ctrl (for Windows) and cmd (for Mac). This allows for cross-platform shortcuts.

Shortcut alternatives

You can also define alternative shortcuts. For that, simply chain the shortcuts with a comma. Here's an example:

shortcuts: {
  disableSelection: 'alt+meta,shift+alt';
}

API

ngx-drag-to-select comes with two main building blocks, a dts-select-container component and a dtsSelectItem directive.

dts-select-container

Inputs

Input	Type	Default	Description
selectedItems	Array	/	Collection of items that are currently selected
selectOnDrag	Boolean	true	Whether items should be selected while dragging
selectOnClick	Boolean	true	Whether items should be selected when clicked
dragOverItems	Boolean	true	Whether drag selection is allowed to start from inside an item
disabled	Boolean	false	Disable selection
disableRangeSelection	Boolean	false	Disable range selection
disableDrag	Boolean	false	Disable selection by dragging with the mouse. May be useful for mobile.
selectMode	Boolean	false	If set to true, a toggle mode is activated similar to the toggleSingleItem shortcut. Useful for mobile.
custom	Boolean	false	If set to true, all default styles for selected items will not be applied.
selectWithShortcut	Boolean	false	If set to true, items can only be selected when single clicking and applying a keyboard shortcut

Here's an example of all inputs in action:

<dts-select-container
  [(selectedItems)]="selectedDocuments"
  [selectOnDrag]="true"
  [disabled]="false"
  [disableDrag]="true"
  [selectMode]="true"
  [custom]="true"
  [selectWithShortcut]="false"
>
  ...
</dts-select-container>

• To get ahold of the selected items you can use a two-way data binding ([()]) aka banana-in-the-box syntax. This means that whenever the selection changes, your property is updated accordingly. It will always reflect the current selection.

• Binding an expression to selectOnDrag will override the default value. When this option is set to false, it will increase the performance but you'll trade this for a slighly worse user experience.

Outputs

Input	Payload Type	Description
select	Array	Event that is fired when the selection changes. The payload ($event) will be the list of selected items.
itemSelected	any	Event that is fired when the item is selected. The payload ($event) will be the item's value
itemDeselected	any	Event that is fired when the item is deselected. The payload ($event) will be the item's value
selectionStarted	None	Event that is fired when the user starts selecting items.
selectionEnded	Array	Event that is fired when the user stops selecting items, typically by releasing the mouse button. The payload will be a list of all selected items

Example:

<dts-select-container
  (select)="someMethod($event)"
  (itemSelected)="itemSelected($event)"
  (itemDeselected)="itemDeselected($event)"
>
  ...
</dts-select-container>

Public Methods

Methods	Description
selectAll()	Select all items within the drag area
clearSelection()	Clear current selection
update()	Recalculate bounding box for the container and its children
selectItems(predicate)	Select all items predicate returns truthy for
deselectItems(predicate)	Deselect all items predicate returns truthy for
toggleItems(predicate)	Toggle all items predicate returns truthy for

To access these methods on the container component you can either use the @ViewChild() decorator

import { Component, ViewChild } from '@angular/core';
import { SelectContainerComponent } from 'ngx-drag-to-select';

@Component({
  ...
})
export class AppComponent {
  @ViewChild(SelectContainerComponent) selectContainer: SelectContainerComponent;

  someMethod() {
    this.selectContainer.clearSelection();
  }
}

or use it within the template with a template reference variable

<button (click)="selectContainer.selectAll()">Select All</button>
<button (click)="selectContainer.clearSelection()">Clear Selection</button>

<dts-select-container #selectContainer="dts-select-container" [(selectedItems)]="selectedDocuments">
  ...
</dts-select-container>

What if I want to use the @ViewChild() decorator but have multiple instances of the dts-select-container in my template?

In that case I would recommend to add template reference variables to your select containers and query them one by one using the variable name.

Here's an example:

<dts-select-container #documents> ... </dts-select-container>

...

<dts-select-container #images> ... </dts-select-container>

In the component you can then query them one by one:

import { Component, ViewChild } from '@angular/core';
import { SelectContainerComponent } from 'ngx-drag-to-select';

@Component({
  ...
})
export class AppComponent {
  @ViewChild('documents') documentContainer: SelectContainerComponent;
  @ViewChild('images') imagesContainer: SelectContainerComponent;

  someMethod() {
    this.documentContainer.clearSelection();
  }

  someOtherMethod() {
    this.imagesContainer.selectAll();
  }
}

Select Box

Each instance of the dts-select-container renders its own select box. Based on the current selection mode, either adding or removing, the container adds corresponding css classes for more flexibility in styling. For adding items to the current selection, either in normal or extended mode, the select box gets a class of dts-adding. For removing items the class will be dts-removing. Both classes can be used to override the look and feel based on the selectio mode.

For instance, the color of the select box, when removing items, can be styled with a separate variable $select-box-removing-color. If the color should be the same for both adding and removing, the $dts-primary variable can be used.

selectItems(predicate)

Iterates over collection of SelectItemDirective's, selecting all items from that collection that meet the condition specified in the predicate function. The predicate is invoked with one argument item, which is equivalent to the value returned by SelectItemDirective.value.

Arguments

predicate ((item: T) => boolean): The function invoked per iteration.

Example

import { Component, ViewChild } from '@angular/core';
import { SelectContainerComponent } from 'ngx-drag-to-select';

@Component({
  ...
})
export class AppComponent {
  @ViewChild(SelectContainerComponent) selectContainer: SelectContainerComponent;

  someMethod() {
    this.selectContainer.selectItems(item => item.id === 1)
  }
}

deselectItems(predicate)

Iterates over collection of SelectItemDirective's, deselecting all items from that collection that meet the condition specified in the predicate function. The predicate is invoked with one argument item, which is equivalent to the value returned by SelectItemDirective.value.

Arguments

predicate ((item: T) => boolean): The function invoked per iteration.

Example

import { Component, ViewChild } from '@angular/core';
import { SelectContainerComponent } from 'ngx-drag-to-select';

@Component({
  ...
})
export class AppComponent {
  @ViewChild(SelectContainerComponent) selectContainer: SelectContainerComponent;

  someMethod() {
    this.selectContainer.deselectItems(item => item.id === 1)
  }
}

toggleItems(predicate)

Iterates over collection of SelectItemDirective's, toggling all items from that collection that meet the condition specified in the predicate function. The predicate is invoked with one argument item, which is equivalent to the value returned by SelectItemDirective.value.

Arguments

predicate ((item: T) => boolean): The function invoked per iteration.

Example

import { Component, ViewChild } from '@angular/core';
import { SelectContainerComponent } from 'ngx-drag-to-select';

@Component({
  ...
})
export class AppComponent {
  @ViewChild(SelectContainerComponent) selectContainer: SelectContainerComponent;

  someMethod() {
    this.selectContainer.toggleItems(item => [1, 2, 3].includes(item.id))
  }
}

dtsSelectItem

The dtsSelectItem directive is used to mark DOM elements as selectable items. It takes an input to control the value that is used when the item was selected. If the input is not specified, it will use the directive instance as a default value.

Inputs

Input	Type	Default	Description
dtsSelectItem	any	Directive Instance	Value that is used when the item is selected
dtsDisabled	boolean	false	Whether the item is selectable or not

Example:

<dts-select-container>
  <ul>
    <li *ngFor="let document of documents" [dtsSelectItem]="document" [dtsDisabled]="document.disabled">
      {{ document.name }}
    </li>
  </ul>
</dts-select-container>

Public Properties

Methods	Type	Description
selected	Boolean	Whether the item is selected or not

You can access this property in a similar why you access methods on the dts-select-container component using either a template reference variable or programmatically with the @ViewChild() decorator.

Example:

<dts-select-container>
  <ul>
    <li [dtsSelectItem]="document" #item *ngFor="let document of documents">
      {{ document.name }}
      <i class="fa fa-check" *ngIf="item.selected"></i>
    </li>
  </ul>
</dts-select-container>

FAQ

Is this library AoT and Universal compatible?

Yes.

Can I use this library with an older version of Angular?

Yep you totally can! But this also means you won't be able to use the latest features. We are not back porting new features due to the maintenance overhead it would create. Severe bugs and security issues, however, are back ported.

What does that mean for you now? We recommend to stay up to date with new Angular versions. If for some reasons you can't then here's an overview of versions you could use with older versions of Angular:

Angular	ngx-drag-to-select
5.x.x	<= 1.1.1
6.x.x - 7.x.x	> 1.1.1 <= 3.1.1
>= 10.x.x <= 12.x.x	>= 4.0.0
>= 13.x.x	>= 5.0.0

To install a specific version run for example npm install ngx-drag-to-select@x.x.x.

Does this library work with mobile?

Yes. This library provides features that you need to implement a mobile version. Check out the Mobile Example, specifically the PhoneComponent component that uses all the tools and features from this library to implement a Google Inbox-like selection experience.

How do I deal with nested scrollable containers?

Suppose, we have the following markup:

<body>
  ...
  <div class="scrollable"><dts-select-container #container="dts-select-container"> ... </dts-select-container></div>
</body>

Here we have another wrapper elements that wraps the dts-select-container. This element is scrollable. The library does not account for any scrollable elements but the dts-select-container itself as well as the body. If you have other nested scrollable containers, and the rendering of the select-box seems to be off, you have to listen for the scroll event on your scrollable element and call update on the dts-select-container. This will make sure that whenever you scroll, the position of the select-container and its items on the screen are re-calculated.

Check out the solution to the problem:

<body>
  ...
  <div class="scrollable" (scroll)="container.update()">
    <dts-select-container #container="dts-select-container"> ... </dts-select-container>
  </div>
</body>

Here we listen for scroll on the div and call container.update() in case the event is fired.

In order not to kill the performance, because the scroll event is called many many times, you may want to throttle it to only call update every 16ms or so.

Want to contribute?

If you want to file a bug, contribute some code, or improve our documentation, read up on our contributing guidelines and code of conduct, and check out open issues.

For developers

If you want to set up ngx-drag-to-select on your machine for development, head over to our developers guide and follow the described instructions.

Versioning

ngx-drag-to-select will be maintained under the Semantic Versioning guidelines. Releases are numbered with the following format:

<MAJOR>.<MINOR>.<PATCH>

1. MAJOR versions indicate incompatible API changes,
2. MINOR versions add functionality in a backwards-compatible manner, and
3. PATCH versions introduce backwards-compatible bug fixes.

For more information on SemVer, please visit http://semver.org.

Licence

MIT © Dominic Elm