Circular shift

circShift.js

// First creates a shallow copy of array,
// then shifts contents circularly according to
// number of steps and direction given

function circularShift(arrayPar, steps, shiftLeft) {
    var array = arrayPar.slice(0);
    for(var i = 0; i < steps; i++) {
        if(shiftLeft)
            array.push(array.shift());
        else
            array.unshift(array.pop());
    }
    return array;
}