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declaration-block-no-duplicate-custom-properties

Disallow duplicate custom properties within declaration blocks.

a { --custom-property: pink; --custom-property: orange; }
/** ↑                        ↑
 * These duplicated custom properties */

This rule is case-sensitive.

The message secondary option can accept the arguments of this rule.

Options​

true​

{
  "declaration-block-no-duplicate-custom-properties": true
}

The following patterns are considered problems:

a { --custom-property: pink; --custom-property: orange; }
a { --custom-property: pink; background: orange; --custom-property: orange }

The following patterns are not considered problems:

a { --custom-property: pink; }
a { --custom-property: pink; --cUstOm-prOpErtY: orange; }

Optional secondary options​

ignoreProperties​

{ "ignoreProperties": ["array", "of", "properties", "/regex/"] }

Ignore duplicates of specific properties.

Given:

{
  "declaration-block-no-duplicate-custom-properties": [
    true,
    { "ignoreProperties": ["--custom-property", "/ignored/"] }
  ]
}

The following patterns are considered problems:

a { --another-custom-property: 1; --another-custom-property: 1; }

The following patterns are not considered problems:

a { --custom-property: 1; --custom-property: 1; }
a { --custom-ignored-property: 1; --custom-ignored-property: 1; }