[adgasf]

I find JavaScript unusable without this operator. Fortunately Babel supports it well.

It makes a great alternative to fiddling with prototypes or wrapper objects when you want to extend something.

For example, this is flat-map implemented as a free function:

    const flatMap = f => {
      if (!f) {
        throw new TypeError('f must be a function');
      }

      return xs => ({
        [Symbol.iterator]: function * () {
          for (const x of xs) {
            yield * f(x);
          }
        }
      });
    };


    // Usage
    const xs = [ 1, 2, 3 ] |> flatMap(x => [ x, -x ]);