function arrayPreviousLess(nums) {
    const output = [-1];
    for (let i = 1; i < nums.length; i++) {
        if (nums[i-1] < nums[i]) {
            output.push(nums[i-1])
        } else {
            output.push(-1)
        }
    }
    return output 
}

//alternate - if lowest value on left should be returned i[-1, 3, -1, 2, 2]
// function arrayPreviousLess(nums) {
//     const output = [-1];
//     let possibleAnswers = [];
//     for (let i = 1; i < nums.length; i++) {
//         if (nums[i-1] < nums[i]) {
//             possibleAnswers = nums.slice(0,i+1).filter((currentValue,index, array) => currentValue < array[array.length-1]).sort((a,b) => b-a)
//             console.log(possibleAnswers)
//             output.push(possibleAnswers.pop())
//         } else {
//             output.push(-1)
//         }
//     }
//     return output 
// } 

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