function arrayPreviousLess(nums) {
    let smth = []
    nums.reverse().map((a,b)=> a>nums[b+1] ? smth.push(nums[b+1]) : smth.push(-1))
    return smth.reverse()
}



/**
* Test Suite 
*/
describe('arrayPreviousLess()', () => {
    it('shift previous postions from the left to a smaller value or store -1', () => {
        // arrange
        const nums = [3, 5, 2, 4, 5];
        
        // act
        const result = arrayPreviousLess(nums);

        // log
        console.log("result: ", result);
        
        // assert
        expect(result).toEqual([-1, 3, -1, 2, 4]);
    });
});