alphabetical-scroll-bar

Alphabetical Scroll Bar

This Github project shows an implementation of the alphabetical-scroll-bar in angular using Ionic Framework. The example can be found in projects/example. Below are images of what it can look like.

Inactive Scroll Bar	Active Scroll Bar

The following is how to use the alphabetical-scroll-bar.

Usage

Install using npm

npm i alphabetical-scroll-bar

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:

<app-alphabetical-scroll 
    [letterMagnification]="Boolean" 
    [exactX]="Boolean" 
    [customAlphabet]="Array<string>"
    [validLetters]="Array<string>" 
    (letterChange)="EventEmitter<string>"
    (endTouch)="EventEmitter<void>">
<app-alphabetical-scroll>

letterMagnification defaults to true. This feature will create a magnification effect on the alphabetical scroll bar when the user touches it.

exactX defaults to false. 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).

customAlphabet allows you to enter your own custom version of the alphabet. It defaults to an all caps alphabet. If the length is not exactly 26 characters, it will default to the all caps alphabet as well.

validLetters is an 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.

letterChange is an eventEmitter. 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.

endTouch is an 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.

You can see how all of these are used in the example project on Github.

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