whatif

Install

npm i whatif

Usage

orSome

Imagine you have a list of conditions and you want to find the which condition cause the branch to be taken.

if (a || b || c) {
  // can't tell which condition is true
  // especially when you want to give users more exact log
  console.log("reason:", "?")
}

Usually we may try to use if statement again to check the exact condition, but it's too verbose and too ugly.

// 😕
if (a || b || c) {
  if (a) {
    console.log("Due to a ...")
  }
  if (b) {
    console.log("Due to b ...")
  }
}

Now, you can use orSome to do this. i.e.

import { orSome } from "whatif"

// simple boolean array
orSome([true, false], (p) => {
  console.log(p.key) // 0.  when pass a boolean array, the key will be the index
})

// with object
orSome(
  [
    { condition: false, key: "one" },
    { condition: true, key: "two", message: "condition two pass" },
  ],
  (p) => {
    console.log(p.key) // two
    console.log(p.message) // condition two pass
  },
)

// mix boolean and object
orSome([false, { condition: true, key: "two" }], (p) => {
  console.log(p.key) // two.
  console.log(p.message) // condition two pass
})

// callback won't be called
orSome([false, false], () => {
  // won't be called
})

But there's a difference you should notice, which is that **EVERY CONDITIONs will be evaluated right away. So if you want to make use of the short circuit, you may wrap a function to lazy the evaluation or just use if statement to make judgement in advance to avoid the Uncaught error:

// ❌ bad case
orSome([
  { condition: !foo.bar, key: "one" },
  { condition: foo.bar.baz, key: "two" }, // foo.bar.baz will be evaluated right now, so it will throw an error here
])

// ✅ good case with if statement in advance:
if (!foo.bar) {
  return
}

orSome([{ condition: foo.bar.baz, key: "one" }], () => {})

// ✅ good case with lazy evaluation:
orSome([{ condition: () => foo.bar.baz, key: "one" }], () => {})