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@jessebeach @stevemao @yangli1990
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label-has-associated-control

Enforce that a label tag has a text label and an associated control.

There are two supported ways to associate a label with a control:

  • Wrapping a control in a label tag.
  • Adding htmlFor to a label and assigning it a DOM ID string that indicates an input on the page.

This rule checks that any label tag (or an indicated custom component that will output a label tag) either (1) wraps an input element (or an indicated custom component that will output an input tag) or (2) has an htmlFor attribute and that the label tag has text content.

How do I resolve this error?

Case: I just want a text label associated with an input.

The simplest way to achieve an association between a label and an input is to wrap the input in the label.

<label>
  Surname
  <input type="text" />
</label>

All modern browsers and assistive technology will associate the label with the control.

Case: The label is a sibling of the control.

In this case, use htmlFor and an ID to associate the controls.

<label htmlFor={domId}>Surname</label>
<input type="text" id={domId} />

Case: My label and input components are custom components.

You can configure the rule to be aware of your custom components.

<CustomInputLabel label="Surname">
  <CustomInput type="text" value={value} />
</CustomInputLabel>

And the configuration:

{
  "rules": {
    "jsx-a11y/label-has-associated-control": [ 2, {
      "labelComponents": ["CustomInputLabel"],
      "labelAttributes": ["label"],
      "controlComponents": ["CustomInput"],
      "depth": 3,
    }],
  }
}

Case: I have two labels for the same input

If the second label is in a different part of the HTML, then the second one can only contain htmlFor but not nesting. You will probably need eslint override comment on the second label.

{/* eslint jsx-a11y/label-has-associated-control: ["error", { assert: "either" } ] */}
<label htmlFor="a">
  Username:
</label>
...
<label htmlFor="a">
  <input id="a" />
</label>

How to manage IDs of input

A common way to think of id with libraries like React is, ids should be avoided since it must be unique on the page, and components need to be reusable. Hence it is tempted to generate id during render-time if id is required. However:

IDs shouldn't be generated in the browser, so that server and client rendering are deterministic. Render-time uuids aren't just a hack, they're actually broken and should never be used.

To restate, every ID needs to be deterministic, on the server and the client, and guaranteed to be unique on the page. EG: For each input, a required ID prop can be passed down from as far up the tree as possible to guarantee uniqueness.

Rule details

This rule takes one optional object argument of type object:

{
  "rules": {
    "jsx-a11y/label-has-associated-control": [ 2, {
      "labelComponents": ["CustomLabel"],
      "labelAttributes": ["inputLabel"],
      "controlComponents": ["CustomInput"],
      "assert": "both",
      "depth": 3,
    }],
  }
}

labelComponents is a list of custom React Component names that should be checked for an associated control. labelAttributes is a list of attributes to check on the label component and its children for a label. Use this if you have a custom component that uses a string passed on a prop to render an HTML label, for example. controlComponents is a list of custom React Components names that will output an input element. assert asserts that the label has htmlFor, a nested label, both or either. Available options: 'htmlFor', 'nesting', 'both', 'either'. depth (default 2, max 25) is an integer that determines how deep within a JSXElement label the rule should look for text content or an element with a label to determine if the label element will have an accessible label.

Fail

function Foo(props) {
  return <label {...props} />
}

Succeed

function Foo(props) {
    const {
        htmlFor,
        ...otherProps
    } = props;

   return <label htmlFor={htmlFor} {...otherProps} />
}

Fail

<input type="text" />
<label>Surname</label>

Succeed

<label>
  <input type="text" />
  Surname
</label>
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