The below script generated a table whose cell color can be updated by clicking on it. I was trying to update the code in a way that on a single click and drag (multi select) it should be able to update the colors of multiple cells and I am out of ideas for it.

const table = document.getElementById("table");

table.innerHTML = "";

// size has a value for number of column and rows
    


for (let i = 0; i < this.size; i++) {
        let tr = document.createElement("tr");

        for (let j = 0; j < this.size; j++) {
            let td = document.createElement("td");
            td.classList.add("border-clr"); 
// backRBG is a variable that stores my color and backRBG2 is a variable that stores my clicked color
                td.style.backgroundColor = backRGB;
                td.onclick= () => {
                    td.style.background= backRBG2 
                }
                tr.appendChild(td);
            }
            table.appendChild(tr);
        }

Thank you in advance.