useButtonType (HTML)

Summary

Rule available since: v2.4.0
Diagnostic Category: lint/a11y/useButtonType
This rule is recommended, meaning it is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
Sources:
- Inspired from react/button-has-type
- Inspired from react-dom/no-missing-button-type
- Inspired from @eslint-react/dom-no-missing-button-type
- Same as svelte/button-has-type
- Same as vue/html-button-has-type
- Same as @html-eslint/require-button-type

How to configure

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{
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  "linter": {
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    "rules": {
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      "a11y": {
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        "useButtonType": "error"
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      }
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    }
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  }
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}

Description

Require an explicit, valid type on every <button>.

A button without a type defaults to submit, which can submit a surrounding form unexpectedly. Use button, submit, or reset to state the intended behavior.

A button element without a type attribute behaves as type="submit". Inside a form, clicking it submits the form, which often reloads the page. That is rarely the intent of a button that opens a menu, toggles a panel, or runs a click handler.

This is easy to miss in Vue, Svelte, and Astro components, because a button rendered by one component can end up inside a form rendered by another. An explicit type makes the button behave the same wherever it’s rendered.

The HTML specification defines three values for type:

button: the button has no default behavior. Use it for buttons handled by JavaScript.
submit: the button submits its form.
reset: the button resets the controls of its form to their initial values.

Browsers treat any other value the same as a missing type, so the rule reports invalid values too.

In Vue, Svelte, and Astro files, the rule ignores type values bound to an expression, such as :type="buttonType" or type={buttonType}, because their value can’t be known statically.

Examples

Invalid

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<button>Do something</button>

code-block.html:1:1 lint/a11y/useButtonType ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Provide an explicit type attribute for the button element.
  
  > 1 │ <button>Do something</button>
      │ ^^^^^^^^
    2 │ 
  
  ℹ The default type of a button is submit, which causes the submission of a form when placed inside a `form` element.
  
  ℹ Allowed button types are: submit, button or reset

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<button type="incorrectType">Do something</button>

code-block.html:1:1 lint/a11y/useButtonType ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Provide a valid type attribute for the button element.
  
  > 1 │ <button type="incorrectType">Do something</button>
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ The default type of a button is submit, which causes the submission of a form when placed inside a `form` element.
  
  ℹ Allowed button types are: submit, button or reset

Clicking this button submits the form instead of clearing it:

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<form action="/search">
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    <input name="query" />
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    <button>Clear</button>
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</form>

code-block.html:3:5 lint/a11y/useButtonType ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Provide an explicit type attribute for the button element.
  
    1 │ <form action="/search">
    2 │     <input name="query" />
  > 3 │     <button>Clear</button>
      │     ^^^^^^^^
    4 │ </form>
    5 │ 
  
  ℹ The default type of a button is submit, which causes the submission of a form when placed inside a `form` element.
  
  ℹ Allowed button types are: submit, button or reset

Valid

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<button type="button">Do something</button>
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<form action="/search">
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    <input name="query" />
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    <button type="reset">Clear</button>
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    <button type="submit">Search</button>
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</form>