Function has

object.js:388–405

(feature)

	}

	function has (feature) {
		var ret;
		var prop = featureMap[feature];

		if (base.isFunction(prop)) {
			// cache return value, ensure boolean
			ret = featureMap[feature] = !!prop(refObj);
		}
		else if (base.isString(prop)) {
			ret = featureMap[feature] = prop in refObj;
		}
		else {
			// return cached evaluate result
			ret = prop;
		}

		return ret;
	}

	function noop (it) { return it; }