Alphabetical Scroll Bar

A very responsive, simple and customizable alphabetical scroll bar (index scrollbar) that can be used in angular projects.

This Github project contains the source code for the alphabetical-scroll-bar and an example of how it is used in an ionic project (projects/example). Here are the basics of how it works, but I strongly suggest looking through the example for how to use it.

Version 2.0.0 and up

New features:

• You can now use your own custom alphabet.
• Added support for desktop (see usage for more info).
• Scroll bar now supports all screen sizes by adding dividers between the letters as the screen size gets smaller.
• Custom magnification curve.
• Many other customization options.

Support

Platform	Support
iOS	Yes
Android	Yes
Web	Yes

Usage

Install using npm

npm i alphabetical-scroll-bar

If you have issues installing, use --force or --legacy-peer-deps to install the peer dependencies

Import in your desired module.ts

import { AlphabeticalScrollBarModule } from 'alphabetical-scroll-bar';

@NgModule({
  imports: [
    ...
    AlphabeticalScrollBarModule
  ],
  ...
})

Here is the template for how data is passed to and from the component:

  <alphabetical-scroll-bar
    [alphabet]="'ABCDEFGHIJKLMNOPQRSTUVWXYZ'"
    [overflowDivider]="'-'"
    [validLetters]="letterGroups"
    [disableInvalidLetters]="true"
    [prioritizeHidingInvalidLetters]="true"
    [letterMagnification]="true"
    [magnifyDividers]="true"
    [magnificationMultiplier]="2"
    [magnificationCurve]="[1, .7, .6, .4, .2, 0]"
    [exactX]="false"
    [navigateOnHover]="true"
    [letterSpacing]="'1%'"
    [offsetSizeCheckInterval]="100"
    (letterChange)="goToLetterGroup($event)"
    (isActive)="!$event && enableScroll()"
  ></alphabetical-scroll-bar>

Input/Output	Parameter	Description	default	type
Input	alphabet	Custom version of the alphabet.	ABCDEFGHIJKLMNOPQRSTUVWXYZ	Array or string
Input	overflowDivider	Custom divider to be used when the screen size is smaller than the scroll bar. Can be set to undefined or null.	·	string or undefined or null
Input	validLetters	Array of the possible letters that are available in the scrollable content. For example, if you only have 5 different letter dividers A, D, F, I, and R, you would want to pass these into validLetters. If you did not, when you tap on Z in the alphabetical scroll bar, nothing will happen. If you do include validLetters, your view would be taken to the next closest letter, which in this case is R. This is not a requirement, but it will make your alphabetical scroll bar much more robust.	ABCDEFGHIJKLMNOPQRSTUVWXYZ	Array
Input	disableInvalidLetters	Boolean that determines whether or not to disable the invalid letters. Disabled letters are greyed out and will not magnify. If you do not, the invalid letters will be shown as disabled.	false	boolean
Input	prioritizeHidingInvalidLetters	If true, the scroll bar will prioritize hiding invalid letters before subsituting overflowDividers. This is useful if you have a lot of invalid letters and you want to show the scroll bar without the invalid letters.	false	boolean
Input	letterMagnification	This will create a magnification effect on the alphabetical scroll bar when the user touches it or hovers over it.	true	boolean
Input	magnifyDividers	This input will magnify the dividers when the user touches them or hovers over them.	false	boolean
Input	magnificationMultiplier	How much to multiply the size of magnified letters.	2	number
Input	magnificationCurve	This is the curve that the magnification will follow as the letters magnify. This input must range between 1 and 0. Closer to one means larger. Closer to zero means smaller. The first index determines the size of the selected letter, the following indexes determine size for neighboring letters. Play around with it to see what looks best for your application.	[1, 0.7, 0.5, 0.3, 0.1]	Array
Input	exactX	When false, this means the user does not have to be accurate along the x direction of the screen (after they have touched the scroll bar), meaning they can slide their finger freely along the x axis while still changing the scroll value. If set to true, the user will have to remain inside the scroll bar to continue navigating (I think false gives it a smoother feel).	false	boolean
Input	navigateOnHover	This means that the user will have to tap on the scroll bar to navigate to a new letter. If set to true, the user will be able to navigate to a new letter by hovering over the scroll bar.	false	boolean
Input	letterSpacing	This is the spacing between letters. It defaults to 1%. Accepts a string with a percentage value (1%) or a number as a pixel value. Percentage is the percent of the scroll bar height.	1%	string or number
Input	offsetSizeCheckInterval	This is the interval in milliseconds that the scroll bar will check to see if the size of the scroll bar has changed. Useful, if e.g. a splitter-component resizes the scroll-bar but not the window itself.	0 (no interval)	number
Output	letterChange	Every time the user scrolls through the alphabetical scroll bar to a new letter, this emitter will output the letter (as a string) that the user scrolled to. This will allow you to scroll to the appropriate letter divider. The example project above shows one method of how this function can be used. You can add things like haptics in the function this calls.	none	none
Output	isActive	EventEmitter that will emit when the user releases their finger from the scroll bar. This is used to stop any unwanted scroll glitches while the user is using the alphabetical scroll bar. See example for more information. (MOBILE ONLY)	none	none

You can see how all of these are used in the projects/example folder.

*Also note that the alphabetical-scroll element must have a high z-index to be above dividers and other elements.