Switch your document to HTML5 by simply changing the doctype at the beginning of the file to <!doctype html>
.
<!doctype html>
<html>
<!-- head -->
<body>
<input type='text' name='foo' placeholder='foo'>
</body>
</html>
If this is not possible in your project, you can then choose to use Javascript to create the same effect as the placeholder attribute:
<input type='text' value='foo'
onfocus="if (this.value === 'foo') {this.value = '';}"
onblur="if (this.value === '') {this.value = 'foo';}">
The second option gives a bit more work, it is not simply checking if the value of the field is "foo" (which was just an example). In this case, using a plugin to do this might be the best solution, for example Placeholder.js .