The easiest way to constrain an HTML input box to uppercase is to use the STYLE attribute inside the INPUT tag.

Suppose you have the following code:

<input type="text" name="big" style="text-transform:uppercase;">

When you type usd, it will appear on screen as USD, but it will be submitted to the server as usd, since STYLE only affects the appearance, not the original data.Here’s the workaround:

This raises another question: why not remove STYLE and just use the JavaScript? The answer is: You can, but users will see the characters “flash” from lower to upper case as they type, which is irritating.”