index - nodef/extra-iterable GitHub Wiki

Get zero-based index for element in iterable.

Similar: index, indexRange, size, isEmpty.

function index(x, i)
// x: an iterable
// i: index (-ve: from right)

const xiterable = require('extra-iterable');

var x = [2, 4, 6, 8];
xiterable.index(x, 1);
// → 1

xiterable.index(x, -1);
// → 3

xiterable.index(x, -10);
// → 0

References