Overview for stepper
CDK stepper provides a foundation upon which more concrete stepper varieties can be built. A stepper is a wizard-like workflow that divides content into logical steps
The base CDK version of the stepper primarily manages which step is active. This includes handling keyboard interactions and exposing an API for advancing or rewinding through the workflow.
A stepper marked as linear requires the user to complete previous steps before proceeding.
For each step, the stepControl attribute can be set to the top level AbstractControl that
is used to check the validity of the step.
There are two possible approaches. One is using a single form for stepper, and the other is using a different form for each step.
Alternatively, if you don't want to use the Angular forms, you can pass in the completed property
to each of the steps which won't allow the user to continue until it becomes true. Note that if
both completed and stepControl are set, the stepControl will take precedence.
When using a single form for the stepper, any intermediate next/previous buttons within the steps
must be set to type="button" in order to prevent submission of the form before all steps are
complete.
When using a form for each step, the workflow is advanced whenever one of the forms is submitted.
If completion of a step in linear stepper is not required, then the optional attribute can be set
on CdkStep in a linear stepper.
By default, steps are editable, which means users can return to previously completed steps and
edit their responses. editable="false" can be set on CdkStep to change the default.
By default, the completed attribute of a step returns true if the step is valid (in case of
linear stepper) and the user has interacted with the step. The user, however, can also override
this default completed behavior by setting the completed attribute as needed.
There are two button directives to support navigation between different steps:
CdkStepperNext and CdkStepperPrevious. When placed inside of a step, these will automatically
add click handlers to advance or rewind the workflow, respectively.
If you want to reset a stepper to its initial state, you can use the reset method. Note that
resetting it will call reset on the underlying form control which clears the value.
- LEFT_ARROW: Focuses the previous step header
- RIGHT_ARROW: Focuses the next step header
- ENTER, SPACE: Selects the step that the focus is currently on
- TAB: Focuses the next tabbable element
- SHIFT+TAB: Focuses the previous tabbable element
The CDK stepper is treated as a tabbed view for accessibility purposes, so it is given
role="tablist" by default. The header of step that can be clicked to select the step
is given role="tab", and the content that can be expanded upon selection is given
role="tabpanel". aria-selected attribute of step header and aria-expanded attribute of
step content is automatically set based on step selection change.
The stepper and each step should be given a meaningful label via aria-label or aria-labelledby.