The pipeline operator is already available in JavaScript

What is this?

This refers to the proposal https://github.com/tc39/proposal-pipeline-operator.

Define the compose function

While ∘ is the official symbol in mathematics, it's not a valid JavaScript identifier. I will be using ᐅ which looks like the pipe operator |> in most languages.

String.prototype.ᐅ = function(f) {
  return f(this)
}

Note that it's a new method on JavaScript's String object. It could work the same on every object (even on Object).

Usage

This is the same example as in the proposal.

function doubleSay (str) {
  return str + ", " + str;
}
function capitalize (str) {
  return str[0].toUpperCase() + str.substring(1);
}
function exclaim (str) {
  return str + '!';
}

let result = "hello"
  .ᐅ (doubleSay)
  .ᐅ (capitalize)
  .ᐅ (exclaim)

result //=> "Hello, hello!"