Identyfikacja błędu
Objaśnienie KS 3.3.1

Tłumacz to Objaśnienie

Intent of Error Identification

The intent of this Success Criterion is to ensure that users are aware that an error has occurred and can determine what is wrong. The error message should be as specific as possible. In the case of an unsuccessful form submission, re-displaying the form and indicating the fields in error is insufficient for some users to perceive that an error has occurred. Screen reader users, for example, will not know there was an error until they encounter one of the indicators. They may abandon the form altogether before encountering the error indicator, thinking that the page simply is not functional. Per the definition in WCAG 2.0, an "input error" is information provided by the user that is not accepted. This includes:

  • information that is required by the web page but omitted by the user, or
  • information that is provided by the user but that falls outside the required data format or allowed values.

For example:

  • the user fails to enter the proper abbreviation in to state, province, region, etc. field;
  • the user enters a state abbreviation that is not a valid state;
  • the user enters a non existent zip or postal code;
  • the user enters a birth date 2 years in the future;
  • the user enters alphabetic characters or parentheses into their phone number field that only accepts numbers;
  • the user enters a bid that is below the previous bid or the minimum bid increment.

If a user enters a value that is too high or too low, and the coding on the page automatically changes that value to fall within the allowed range, the user's error would still need to be described to them as required by the success criterion. Such an error description telling the person of the changed value would meet both this success criterion (Error Identification) and Success Criterion 3.3.3 (Error Suggestion).

The identification and description of an error can be combined with programmatic information that user agents or assistive technologies can use to identify an error and provide error information to the user. For example, certain technologies can specify that the user's input must not fall outside a specific range, or that a form field is required. Currently, few technologies support this kind of programmatic information, but the Success Criterion does not require, nor prevent it.

It is perfectly acceptable to indicate the error in other ways such as image, color etc, in addition to the text description.

See also 3.3.3: Error Suggestion.

Benefits of Error Identification

  • Providing information about input errors in text allows users who are blind or colorblind to perceive the fact that an error occurred.
  • This Success Criterion may help people with cognitive, language, and learning disabilities who have difficulty understanding the meaning represented by icons and other visual cues.

Examples of Error Identification

  • Identifying errors in a form submission

    An airline Web site offers a special promotion on discounted flights. The user is asked to complete a simple form that asks for personal information such as name, address, phone number, seating preference and e-mail address. If any of the fields of the form are either not completed or completed incorrectly, an alert is displayed notifying the user which field or fields were missing or incorrect.

    This Success Criterion does not mean that color or text styles cannot be used to indicate errors. It simply requires that errors also be identified using text. In this example, two asterisks are used in addition to color.

  • Providing multiple cues

    The user fails to fill in two fields on the form. In addition to describing the error and providing a unique character to make it easy to search for the fields, the fields are highlighted in yellow to make it easier to visually search for them as well.

Resources for Error Identification

Techniques for Error Identification

Sufficient Techniques for Error Identification

Situation A: If a form contains fields for which information from the user is mandatory.

  1. Providing a text description that identifies the field as mandatory
  3. Providing client-side validation and alert

Situation B: If information provided by the user is required to be in a specific data format or of certain values.

  4. G84: Providing a text description when the user provides information that is not in the list of allowed values
  5. Providing a text description when user input falls outside the required format or values
  6. Providing client-side validation and alert
  7. Providing client-side validation and adding error text via the DOM

Additional Techniques (Advisory) for Error Identification

Failures for Error Identification