possible-js
Purpose
It's a tiny library to make working with TypeScripts --strictNullChecks more user-friendly.
This library is designed to protect against both null and undefined values,
but has the ability to support custom checks as well.
Installation
yarn add possible-jsUsage
Given this potentially undefined button...
import { ofPossible } from 'possible-js'; const btnOrUndefined = document.getElementById('btn');... get it...
// if button is present, get it, or fail fast.const button = ofPossible(btnOrUndefined).getOrThrow(); // if button is present, get it, or return a new one.const button = ofPossible(btnOrUndefined).getOrReturn(new HTMLButtonElement());... or, do something with it...
// if button is present, click it, or fail fast.ofPossible(btnOrUndefined).doOrThrow(b => b.click()); // if button is present, click it, or do nothing.ofPossible(btnOrUndefined).doOrIgnore(b => b.click());... or, map its properties...
// if button is present, return its dimensions, or fail fast.const dim = ofPossible(btnOrUndefined).mapOrThrow(b => ({ w: b.offsetWidth, h: b.offsetHeight })); // if button is present, return its dimensions, or return a default value.const dim = ofPossible(btnOrUndefined).mapOrReturn(b => ({ w: b.offsetWidth, h: b.offsetHeight }), { w: 0, h: 0 });... or, pipe multiple functions...
import { ofPossible, mapOrThrow, doOrThrow } from 'possible-js'; ofPossible(btnOrUndefined).pipe( mapOrThrow(b => b.parentElement), // if button is present find its parent, or fail fast mapOrThrow(p => p.nextElementSibling), // if parent is present find its sibling, or fail fast mapOrThrow(s => s.firstElementChild), // if sibling is present, find its first child, or fail fast doOrThrow(c => c.innerHTML = '<span>hello</span>') // if first child is present insert html, or fail fast);... or, use a custom check before performing one of the above actions
// if button is present and its text is equal to 'SUBMIT', click it, otherwise throw an error.ofPossible(btnOrUndefined).doOrThrow(b => b.click(), { checkFn: b => !!b && b.innerText === 'SUBMIT' });