If browser does not support HTML5 placeholder attribute, simulate the effect with jQuery

placeholder_polyfill.js

$('.search-box').each(function(){
	if(!Modernizr.input.placeholder){
		var $el = $(this),
			placeholderText = $el.attr('placeholder');

		if( placeholderText ){
			$el.addClass('placeholder-text').val(placeholderText)
			.bind('focus', function() {
				if( $el.val() === placeholderText ) {
					$el.val('').removeClass('placeholder-text');
				}
			}).bind('blur', function() {
				if( $el.val() === '' ) {
					$el.val(placeholderText).addClass('placeholder-text');
				}
			});
		}
	}
});