function arrayPreviousLess(nums) {
    //  write code here.
    
    const results = [];
    
    for (let i = 0; i < nums.length; i++){
        
        const previousNum = nums[i - 1];
        const currentNum = nums[i];
        
        if(previousNum < currentNum){
            
            results.push(previousNum)
        } else {

            results.push(-1)
        }
    }
    

    
    return results
    
    
}



/**
* 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]);
    });
});