Shifts array element up, down or custom
$ npm install array-shiftlet arrayShift = require('array-shift');
let arr = [1,2,3,4,5];
// up(array, index)
arrayShift.down(arr, 0);
console.log(arr); // -> [2,1,3,4,5]
// down(array, index)
arrayShift.up(arr, 0);
console.log(arr); // -> [1,2,3,4,5]
// custom(array, fromIndex, toIndex)
arrayShift.custom(arr, 0, 4)
console.log(arr); // -> [2,3,4,5,1]