Javascript div doesn't work

Question

var udiv = document.createElement('div');
var div = document.createElement("div");
div.style.width = "100px";
div.style.height = "100px";
div.style.background = "red";
div.style.color = "white";
div.innerHTML = "Hello";
div.appendChild(udiv);

I've been trying to get this to work, but when I open the page there's nothing there. I know the Javascript file works because everything else shows up, but the div doesn't. There's no error.

Answer 1

您已将udiv附加到div ，但从未将div附加到 DOM。

Answer 2

But both are new elements, Append those elements to an already existing element or to the body ,

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.
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div.appendChild(udiv);
document.body.appendChild(div)

Answer 3

您没有将div对象附加到 DOM

document.body.appendChild(div);