ko.extenders[ruleName] = function()

in google-cloud-server/src/main/resources/buildServerResources/knockout.validation-2.0.3.js [512:542]

• 15 lines of code
• 5 McCabe index (conditional complexity)

			ko.extenders[ruleName] = function (observable, params) {
				//params can come in a few flavors
				// 1. Just the params to be passed to the validator
				// 2. An object containing the Message to be used and the Params to pass to the validator
				// 3. A condition when the validation rule to be applied
				//
				// Example:
				// var test = ko.observable(3).extend({
				//	  max: {
				//		  message: 'This special field has a Max of {0}',
				//		  params: 2,
				//		  onlyIf: function() {
				//					  return specialField.IsVisible();
				//				  }
				//	  }
				//  )};
				//
				if (params && (params.message || params.onlyIf)) { //if it has a message or condition object, then its an object literal to use
					return kv.addRule(observable, {
						rule: ruleName,
						message: params.message,
						params: utils.isEmptyVal(params.params) ? true : params.params,
						condition: params.onlyIf
					});
				} else {
					return kv.addRule(observable, {
						rule: ruleName,
						params: params
					});
				}
			};