Detect Placeholder support for form elements

hasSupport for attribute

function hasSupport(elem, attribute) {
	return attribute in elem;
}

$('body').delegate('textarea', 'focus input change keydown keyup', function(e) {
	var $textArea = $(this);

	if (!hasSupport($textArea[0], 'placeholder')) {
		var placeholderText = $textArea.attr("placeholder");
		if (this.value === $textArea.data("placeholder")) {
			this.value = "";
		}
	}
}).delegate('textarea', 'blur', function(e){
	var $textArea = $(this);
	if (!hasSupport($textArea[0], 'placeholder')) {
		if (this.value === "") {
			this.value = $textArea.data("placeholder");
			$textArea.addClass('blur');
		}
	}
});