Ramda represents a distinct alternative to traditional vanilla JavaScript

I'm feeling a bit confused about how Ramda really works. I found this code and I'm not entirely sure how it functions.

const render = curry(
  (renderer, value) => is(Function, renderer) && renderer(value)
);

I just need to grasp an easier way to convert is(Function, renderer) into Vanilla JS. I attempted to create checks for strings, numbers, and objects, but the check only uses 'string' type and doesn't include Function.

Answer №1

Ramda, the fantastic open-source library, provides a seamless implementation that can be viewed here.

function is(Ctor, val) {
  return val instanceof Ctor ||
    val != null && (
      val.constructor === Ctor ||
      (Ctor.name === 'Object' && typeof val === 'object'));
}

Answer №2

This particular feature ensures a safe execution of the renderer function only if it truly exists as a function. It seems that the initial developer considered the scenario where it could either be undefined or not a function.

const render = curry(
  (renderer, value) => is(Function, renderer) && renderer(value)
);

The equivalent vanilla JavaScript version would look like:

const render = (renderer = () => {}, value = null) => renderer(value);
// or
const render = (renderer, value) => renderer?.(value)

Answer №3

In many of the code I write, I frequently utilize the keyword is -

const is = (T, t) =>
  t?.constructor === T
 
console.log(is(Array, 1)) // false
console.log(is(Array, null)) // false
console.log(is(Array, {a: 1})) // false
console.log(is(Array, [2])) // true

console.log(is(Object, 1)) // false
console.log(is(Object, undefined)) // false
console.log(is(Object, [1,2])) // false
console.log(is(Object, {a:1})) // true

console.log(is(Number, 1)) // true
console.log(is(Number, NaN)) // true
console.log(is(Number, undefined)) // false
console.log(is(Number, [3])) // false
console.log(is(Number, x => x + 1)) // false

console.log(is(Function, x => x + 1)) // true
console.log(is(RegExp, /foo/g)) // true
console.log(is(String, "hello")) // true
.as-console-wrapper { min-height: 100%; top: 0; }

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