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In this lecture, we will begin validating the password fields by checking if they match.

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As we discussed before, we will expect this validator to be applied to a form group instead of a control.

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The validator should have access to the fields that should have matching values to get started.

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Let's open the register validators file.

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In this class, we will add a static method called Match.

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If you're not familiar with the static method, let me quickly run down what this feature is for.

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We can think of classes as blueprints for objects whenever we want to invoke a method or access a property.

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We need to create an instance out of the class.

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I'll add a comment below for clarity.

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Let's say the match method did not have the static keyword.

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If we want to call this method, a new instance of the Register of Validators class must be created.

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After creating the instance, we will be able to call this method.

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Static methods are different if a method is static.

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We can directly call the method without creating a new instance.

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Static methods are beneficial for creating utility methods.

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If we don't need to maintain an object state, converting a method into a static method will result

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in writing less code.

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Alternatively, we could define a function instead of writing a static method inside a class.

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However, you may want to define a static method for grouping the method in a class.

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The name of our class is called register validators.

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If we want to define multiple validators for the registration form, we can define them under a single

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namespace for clarity.

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It's an optional step, but I think it's worth grouping our validators in a single class.

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Adding the static keyword to a method will reduce the amount of code we'll have to write.

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There are some limitations with static methods.

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They do not have access to an object's properties or methods.

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For example, let's add a property to the class called test with an initial value of five.

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Inside the match method, we will log the test property.

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TypeScript will throw an error.

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It says the test property is not defined in the class.

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However, clearly it is the reason it's not detecting the test property is because static methods don't

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have access to an object's properties or methods since we're not creating an instance out of the class.

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The methods and properties are never instantiated using the.

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This key word is prohibited within a static method.

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If we were to remove the static method, the error would go away.

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Always keep this limitation in mind.

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Static methods are great for creating utility methods, but are limited with their scope.

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I'll add the static keyword back in.

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Let's move on to working on the validator in the following lecture.