How do you automatically set text box to Uppercase?

Question

You've put the style attribute on the <img> tag, instead of the <input>.

It is also not a good idea to have the spaces between the attribute name and the value...

<input type="text" class="normal" 
       name="Name" size="20" maxlength="20" 
       style="text-transform:uppercase" /> 
<img src="../images/tickmark.gif" border="0" />

Please note this transformation is purely visual, and does not change the text that is sent in POST.

I think the most robust solution that will insure that it is posted in uppercase is to use the oninput method inline like:

<input oninput="this.value = this.value.toUpperCase()" />

EDIT

Some people have been complaining that the cursor jumps to the end when editing the value, so this slightly expanded version should resolve that

<input oninput="let p=this.selectionStart;this.value=this.value.toUpperCase();this.setSelectionRange(p, p);" />

The answers with the text-transformation:uppercase styling will not send uppercased data to the server on submit - what you might expect. You can do something like this instead:

For your input HTML use onkeydown:

<input name="yourInput" onkeydown="upperCaseF(this)"/>

In your JavaScript:

function upperCaseF(a){
    setTimeout(function(){
        a.value = a.value.toUpperCase();
    }, 1);
}

With upperCaseF() function on every key press down, the value of the input is going to turn into its uppercase form.

I also added a 1ms delay so that the function code block triggers after the keydown event occured.

UPDATE

Per recommendation from Dinei, you can use oninput event instead of onkeydown and get rid of setTimeout.

For your input HTML use oninput:

<input name="yourInput" oninput="this.value = this.value.toUpperCase()"/>

The problem with the first answer is that the placeholder will be uppercase too. In case you want ONLY the input to be uppercase, use the following solution.

In order to select only non-empty input element, put required attribute on the element:

<input type="text" id="name-input" placeholder="Enter symbol" required="required" />

Now, in order to select it, use the :valid pseudo-element:

#name-input:valid { text-transform: uppercase; }

This way you will uppercase only entered characters.

try

<input type="text" class="normal" 
       style="text-transform:uppercase" 
       name="Name" size="20" maxlength="20"> 
 <img src="../images/tickmark.gif" border="0"/>

Instead of image put style tag on input because you are writing on input not on image