` element reveals a set of nested message `divs`
@@ -62,9 +51,6 @@ but only if the `name` is invalid and the control is either `dirty` or `touched`
There are messages for `required`, `minlength`, and `forbiddenName`.
-{@a why-check}
-
-
@@ -72,53 +58,37 @@ There are messages for `required`, `minlength`, and `forbiddenName`.
#### Why check _dirty_ and _touched_?
You may not want your application to display errors before the user has a chance to edit the form.
-The checks for `dirty` and `touched` prevent errors from showing until the user changes the value
-(turning the control dirty) or blurs the form control element (setting the control to touched).
+The checks for `dirty` and `touched` prevent errors from showing until the user
+does one of two things: changes the value,
+turning the control dirty; or blurs the form control element, setting the control to touched.
-
-
-Check out the [live example](guide/form-validation#live-example) for the full template-driven component.
-
-
-
-{@a reactive}
-
## Reactive form validation
-In a reactive form, the source of truth is the component class. Instead of adding validators
-through attributes in the template, you add validator functions directly to the form control
-model in the component class. These functions are then called whenever the value of the
-control changes.
+In a reactive form, the source of truth is the component class. Instead of adding validators through attributes in the template, you add validator functions directly to the form control model in the component class. Angular then calls these functions whenever the value of the control changes.
### Validator functions
There are two types of validator functions: sync validators and async validators.
-* **Sync validators**: functions that take a control instance and immediately return either a
-a set of validation errors or `null`. These can be passed in as the second argument when
-you instantiate a `FormControl`.
+* **Sync validators**: functions that take a control instance and immediately return either a set of validation errors or `null`. You can pass these in as the second argument when you instantiate a `FormControl`.
* **Async validators**: functions that take a control instance and return a Promise
-or Observable that later emits a set of validation errors or `null`. These can be passed
-in as the third argument when you instantiate a `FormControl`.
+or Observable that later emits a set of validation errors or `null`. You can
+pass these in as the third argument when you instantiate a `FormControl`.
-Note: for performance reasons, async validators are only run if all sync validators pass. Each
-must complete before errors are set.
+Note: for performance reasons, Angular only runs async validators if all sync validators pass. Each must complete before errors are set.
### Built-in validators
-You can choose to [write your own validator functions](guide/form-validation#custom-validator), or you can use some of our built-in
-validators.
+You can choose to [write your own validator functions](guide/form-validation#custom-validators), or you can use some of
+Angular's built-in validators.
-The same built-in validators that were available as attributes in template-driven forms -
-`required`, `minlength`, etc - are all available to use as functions from the
-`Validators` class. For a full list of built-in validators, see the [Validators](api/forms/Validators)
-API reference.
+The same built-in validators that are available as attributes in template-driven forms, such as `required` and `minlength`, are all available to use as functions from the `Validators` class. For a full list of built-in validators, see the [Validators](api/forms/Validators) API reference.
-If our hero form is updated to be a reactive form, we'll want to use some of the same
-built-in validators (this time, in function form). See below:
+To update the hero form to be a reactive form, you can use some of the same
+built-in validators—this time, in function form. See below:
{@a reactive-component-class}
@@ -127,15 +97,12 @@ built-in validators (this time, in function form). See below:
Note that:
-* The name control sets up two built-in validators - `Validators.required` and `Validators.minLength(4)` - and
-one custom validator, `forbiddenNameValidator` (more on that [later](guide/form-validation#custom-validator)).
-* As these validators are all sync validators, they are passed in as the second argument.
-* Multiple validators are supported by passing the functions in as an array.
-* A few getter methods have been added. In a reactive form, you can always access any form control
-through the `get` method on its parent group, but sometimes it's useful to define getters as shorthands
+* The name control sets up two built-in validators—`Validators.required` and `Validators.minLength(4)`—and one custom validator, `forbiddenNameValidator`. For more details see the [Custom validators](guide/form-validation#custom-validators) section in this guide.
+* As these validators are all sync validators, you pass them in as the second argument.
+* Support multiple validators by passing the functions in as an array.
+* This example adds a few getter methods. In a reactive form, you can always access any form control through the `get` method on its parent group, but sometimes it's useful to define getters as shorthands
for the template.
-{@a reactive-component-template}
If you look at the template for the name input again, it is fairly similar to the template-driven example.
@@ -149,28 +116,19 @@ Key takeaways:
* The `required` attribute is still present. While it's not necessary for validation purposes,
you may want to keep it in your template for CSS styling or accessibility reasons.
-
-
-Run the [live example](guide/form-validation#live-example) to see the full reactive form component.
-
-
-
-
-{@a custom-validator}
## Custom validators
-The built-in validators won't always match the exact use case of your application. Sometimes you'll want to
-create a custom validator.
+Since the built-in validators won't always match the exact use case of your application, sometimes you'll want to create a custom validator.
-You may remember the `forbiddenNameValidator` function from the examples above. Here's what the definition of
-that function looks like:
+Consider the `forbiddenNameValidator` function from previous
+[examples](guide/form-validation#reactive-component-class) in
+this guide. Here's what the definition of that function looks like:
-The function is actually a factory that takes a regular expression to detect a _specific_ forbidden name
-and returns a validator function.
+The function is actually a factory that takes a regular expression to detect a _specific_ forbidden name and returns a validator function.
In this sample, the forbidden name is "bob", so the validator will reject any hero name containing "bob".
Elsewhere it could reject "alice" or any name that the configuring regular expression matches.
@@ -179,7 +137,7 @@ The `forbiddenNameValidator` factory returns the configured validator function.
That function takes an Angular control object and returns _either_
null if the control value is valid _or_ a validation error object.
The validation error object typically has a property whose name is the validation key, `'forbiddenName'`,
-and whose value is an arbitrary dictionary of values that you could insert into an error message (`{name}`).
+and whose value is an arbitrary dictionary of values that you could insert into an error message, `{name}`.
### Adding to reactive forms
@@ -192,9 +150,9 @@ to the `FormControl`.
### Adding to template-driven forms
In template-driven forms, you don't have direct access to the `FormControl` instance, so you can't pass the
-validator in that way. Instead, you'll want to add a directive to the template.
+validator in like you can for reactive forms. Instead, you need to add a directive to the template.
-The corresponding `ForbiddenValidatorDirective` is a wrapper around the `forbiddenNameValidator`.
+The corresponding `ForbiddenValidatorDirective` serves as a wrapper around the `forbiddenNameValidator`.
Angular recognizes the directive's role in the validation process because the directive registers itself
with the `NG_VALIDATORS` provider, a provider with an extensible collection of validators.
@@ -209,8 +167,7 @@ comes together:
-Once the `ForbiddenValidatorDirective` is ready, you can simply add its selector (`forbiddenName`)
-to any input element to activate it. For example:
+Once the `ForbiddenValidatorDirective` is ready, you can simply add its selector, `forbiddenName`, to any input element to activate it. For example:
@@ -228,23 +185,24 @@ doesn’t have a `forbiddenName`.