index - nodef/extra-array GitHub Wiki
Get zero-based index for an element in array.
Similar: index, indexRange, size, isEmpty.
function index(x, i)
// x: an array
// i: ±index
const xarray = require('extra-array');
var x = [2, 4, 6, 8];
xarray.index(x, 1);
// → 1
xarray.index(x, -1);
// → 3
xarray.index(x, -10);
// → 0