Array.prototype.findIndex(fn, startIndex = 0)

# Cyril Auburtin (6 months ago)

It should be possible to add a second optional argument to the find and findIndex array methods, similarly to indexOf

# Andrea Giammarchi (6 months ago)

isn't the second argument already reserved for the context?

[1, 2, 3].findIndex(function (i) { return i == this; }, 2);
// 1
# Jordan Harband (6 months ago)

I believe every array iteration method that takes a callback, except for reduce and reduceRight, take an optional receiver as the last argument (the this value), so they can't be meaningfully/ergonomically extended.