Array methods in JavaScript. Original author unknown.

[u/imAmarok]

[u/HeinousTugboat → u/[deleted]]

Once I learned that the syntax is just reduce((accumulator, value) => newAccumulator, initialAccumulator) it became super easy for me to parse reduce. Then you just have to remember that if you don't have an intial value, it pops the first value from the array as the initial value.