Finds indices of values passing a test.
Alternatives: search, searchRight, searchAll.
Similar: search, scan, find.
This is part of package extra-array.
array.searchAll(x, ft);
// x: an array
// ft: test function (v, i, x)const array = require("extra-array");
var x = [1, 2, 3, 2, 5];
array.searchAll(x, 2);
// [ 1, 3 ] ^ ^
var x = [1, 2, 3, -2, 5];
array.searchAll(x, 2, (a, b) => Math.abs(a) - Math.abs(b));
// [ 1, 3 ] ^ ^
array.searchAll(x, 2, null, v => Math.abs(v));
// [ 1, 3 ] ^ ^