The Code

                
                function getValues(){
                    let startValue = document.getElementById('startValue').value;
                    let endValue = document.getElementById('endValue').value;

                    startValue = parseInt(startValue);
                    endValue = parseInt(endValue);
                
                    if (Number.isInteger(startValue) && Number.isInteger(endValue)){
                        let numbersArray = generateNumbers(startValue, endValue);
                        displayNumbers(numbersArray);
                    } else {
                        Swal.fire(
                            {
                                icon: 'error',
                                title: 'You goofed it...',
                                text: 'Only integers are allowed for this input.',
                            }
                        );
                    }
                       
                }
                
                function generateNumbers(start, end){
                    let numbers = [];
                
                    for(let value = start; value<= end; value++){
                        numbers.push(value);
                    }
                
                    return numbers; 
                }
                
                function displayNumbers(numbersArray){
                    let tableBody = document.getElementById('results');
                
                    let tableHtml = "";
                
                    for(let index = 0; index < numbersArray.length; index++){
                        let value = numbersArray[index];
                        let className = '';
                        if (value % 2 == 0){
                            className = 'even';
                        }
                        else {
                            className = 'odd';
                        }
                
                        if (index % 5 == 0){
                            tableHtml += '';
                        }
                
                        let tableRow = `${value}`;
                
                        tableHtml = tableHtml + tableRow;
                
                        if ((index + 1) % 5 == 0) {
                            tableHtml += '';
                        }
                    }
                
                    tableBody.innerHTML = tableHtml;
                }
                
            

The code is structured in three functions.

getValues()

This function grabs the values that the user's input. It takes the string and turns it into an array that the rest of the code can use.

generateNumbers(start, end)

This function takes the starting value and the ending value and generates the numbers between them.

displayNumbers(numbersArray)

This last function then formats the data so it can be presented properly on the site.