How to center text horizontally and vertically in a div

I had been trying to center the text in div element both vertically and horizontally. I had been searching for the solutions to this, but couldn’t find anything which completely described my problem and the solution. Let me first explain what exactly I was trying to do: I was adding a div element dynamically to a web page using Javascript. The div element should have a known height and width and the text should be positioned in the center of the div element. Let me start from the beginning.

How to create a div element dynamically using `javascript`: For this, we will use the `createElement` method.
```
var myDivElement = document.createElement('div');
```
You can then specify absolute position (known beforehand) in the document using css styles and associating a class with the element using:
```
myDivElement.className += ' my-div-class';
```
The position can then be defined in a css file.

Alternatively, if the position of the div element is not known beforehand, then it can be associated in the javascript code itself using:
```
myDivElement.style.position = 'absolute';
myDivElement.style.top = posY + 'px';
myDivElement.style.left = posX + 'px';
```
We can then add any code inside the div element using:
```
myDivElement.innerHTML = "Some HTML";
```
The next step is to add the created element to the document (or any other element on the document):
```
someExistingElement.appendChild(myDivElement);
```
The element can also be removed later using:
```
someExistingElement.removeChild(myDivElement);
```
The next step is to align the text in the div element to center. The text can be aligned to center using the following css styles:
```
vertical-align : middle;
text-align : center;
```
However, its not as simple as it sounds. Unless we define the width and line-height of the div element, this has no affect on the alignment. Define the width and line-height of the div element:
```
width: 20px;
line-height: 20px;
```
If these values are not known beforehand, these can also be assigned in the javascript code:
```
myDivElement.style.width = myWidth + 'px';
myDivElement.style.lineHeight = myHeight + 'px';
```