function createSquareDivs(){
    const container = document.querySelector("#container");

    for (let i = 0; i < 16; i++){
        let div = document.createElement("div"); // first div to contain a row

        for (let j = 0; j < 16; j++){
            let div2 = document.createElement("div"); // second div to fill the columns
            div2.style.width = "30px";
            div2.style.height = "30px";
            div2.style.display = "inline-block";
            div2.addEventListener("mouseenter", mouseEnterDiv(div2)) // Event isn't added
            div.appendChild(div2);

        }
        container.appendChild(div);
    }
}

function mouseEnterDiv(div){
    let red = Math.floor(Math.random() * 256);
    let green = Math.floor(Math.random() * 256);
    let blue = Math.floor(Math.random() * 256);
    div.style.background = `rgb("${red}","${green}","${blue}")`;
}

createSquareDivs()