Finds first index of a value.
Alternatives: indexOf, lastIndexOf.
Similar: search, indexOf, isValue, includes.
This is part of package extra-array.
array.indexOf(x, v, [i]);
// x: an array
// v: search value
// i: start index (0)
const array = require("extra-array");
var x = [1, 2, 3, 2, 5];
array.indexOf(x, 2);
// 1 ^
var x = [1, 2, 3, 2, 5];
array.indexOf(x, 2, 2);
// 3 ^