@extra-array/splice

array.splice(x, i, [n], ...vs);
// x:  an array
// i:  remove index
// n:  number of values to remove (rest)
// vs: values to insert

const array = require("extra-array");

var x = [1, 2, 3, 4, 5];
array.splice(x, 2);
// [ 1, 2 ]

array.splice(x, 2, 2);
// [ 1, 2, 5 ]

array.splice(x, 2, 2, 30, 40);
// [ 1, 2, 30, 40, 5 ]