Schema.org Microdata validation plugin

I am starting to write a plugin that is aiming to validate a piece of mark up against requirements of schema.org.

I was hoping if I could get some more tips on how to improve the structure of my code. Is this how you would go about this if you were to do it?

```
$.fn.hasAttr = function(name) {
return this.attr(name) !== undefined;
};

$.fn.outerHTML = function(s) {
return $(this).clone().wrap('').parent().html();
};

$.fn.getOpeningTag = function (s) {
return $(this).outerHTML().slice(0, $(this).outerHTML().indexOf(">") + 1)
}

$.fn.validateSchema = function(options) {

var defaults = {
// for a list of international postcode regex see: http://www.thalesjacobi.com/Regex_to_validate_postcodes
// The one used in the example is from the UK
localPostCodeFormat: new RegExp("^([Gg][Ii][Rr] 0[Aa]{2})|((([A-Za-z][0-9]{1,2})|(([A-Za-z][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-Za-z][0-9][A-Za-z])|([A-Za-z][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) {0,1}[0-9][A-Za-z]{2})$"),
utilities : {
missAtrr : function (target, attrName) {
if (!target.hasAttr(attrName)){
defaults.returnError(target, "The element " + target.getOpeningTag() + " is missing the required attribute " + attrName);
}
},
isValidPostCode : function (target) {
if (!defaults.localPostCodeFormat.test(target.text())) {
defaults.returnError(target, target.getOpeningTag() + " does not have a valid post code");
}

}
},
returnError : function (target, errorMessage) {
var errorContainer = $('');
target.before(errorContainer);
errorContainer.css({
'color' : 'red',
'border': 'solid 1px red'
}).text(errorMessage);
} // more utils to be added
};
// Extend our default options with thos

This will return false for attr in such an object {'attr': undefined}:

$.fn.hasAttr = function(name) {  
   return this.attr(name) !== undefined;
};

If this is not exactly what you want, have a look at related posts (one, two) and search for much more.

This (and similars) will always evaluate to true, if schemaElements object has the postalAddress key:

if (schemaElements.postalAddress){
    defaults.utilities.missAtrr(schemaElements.postalAddress, "itemscope");
}

here's an example session from Chrome developer console:

var rules = {'a': $('html').find('#idontexist')};
rules.a;
// []
if (rules.a) {console.log(true)} else {console.log(false)};
// true

Be consistent with ; at the end of the lines.

StackExchange Code Review Q#7745, answer score: 4