javascript var into input value

can someone help me out getting a javascript var inside the value of a form input value?

I'm a newbie in javascript but can give you开发者_开发知识库 my solution in php. ("Just use php" isn't an option because it have to be client-based :D )

<?php
$value = "Hello!";
?>

<form name="settings" action="">
   <input name="color" value="<?php echo $value; ?>" />
</form>

Thanks in advance

Like this:

document.forms["settings"].color.value = "your value goes here...";

<?php
$value = "Hello!";
?>

<form name="settings" action="">
   <input name="color" value="" />
</form>  
<script>
document.forms["settings"].color.value = "<?php echo $value;?>";
</script>