Sass meta.mixin-exists()

Intermediate
8 min read
Updated: Nov 2026
5 examples
Dart Sass
Sass meta.mixin-exists checking whether a mixin name is defined
Definition

Definition and Usage

meta.mixin-exists($name, $module: null) returns a boolean: whether a mixin named $name is defined. Load it with @use "sass:meta".

Official sample.

meta.mixin-exists("shadow-none") is false until you define @mixin shadow-none, then true.

Pass $module for namespaces.

After @use "utils", check module members with $module: "utils". The value can also be a module value.

Yes/no only.

To include the mixin dynamically, use meta.get-mixin plus meta.apply. Guard optional names with mixin-exists first.

Syntax

Syntax

SCSS
@use "sass:meta";

meta.mixin-exists($name, $module: null); //=> boolean

meta.mixin-exists("shadow-none"); // false until defined
@mixin shadow-none { box-shadow: none; }
meta.mixin-exists("shadow-none"); // true

meta.mixin-exists("center", $module: "utils"); // after @use "utils"

// Global alias (legacy): mixin-exists($name) — no $module
// Prefer meta.mixin-exists after @use "sass:meta"

Pattern: choose a name (and optional module) → check mixin-exists → branch or call get-mixin / @include.

Reference

Name and $module

How lookups work:

CallLooks inExample
meta.mixin-exists("shadow-none")Current scope (no namespace)User @mixin in this file
meta.mixin-exists("center", $module: "utils")The utils @use namespaceutils.center
Before defining the mixin—false
After @mixin / in moduleMatching scopetrue
vs other member checks.

Use meta.function-exists for functions and meta.global-variable-exists for globals. Prefer these over deprecated meta.feature-exists.

Code

SCSS Examples

Examples use @use "sass:meta". Open View Compiled CSS for verified Dart Sass output (matches official Sass docs samples where shown).

Example 1 — Custom Mixin Before and After

A name is missing until you define it (official shadow-none idea).

SCSS
@use "sass:meta";

.before {
  --shadow: #{meta.mixin-exists("shadow-none")};
}

@mixin shadow-none {
  box-shadow: none;
}

.after {
  --shadow: #{meta.mixin-exists("shadow-none")};
}

.btn {
  @include shadow-none;
}

How It Works

  1. Before the mixin, the check is false.
  2. @mixin shadow-none defines it.
  3. Afterward, the same check is true.
  4. Matches the official Sass docs sample idea.

Example 2 — Check a Mixin in Another Module

Use $module for mixins loaded with @use.

SCSS
@mixin center {
  display: grid;
  place-items: center;
}
SCSS
@use "sass:meta";
@use "utils";

.probe {
  --utils-center: #{meta.mixin-exists("center", $module: "utils")};
  --bare-center: #{meta.mixin-exists("center")};
}

How It Works

  1. @use "utils" loads the partial.
  2. $module: "utils" finds center.
  3. Bare "center" does not see the namespaced mixin.
  4. Match the namespace string used in this file.

Example 3 — Optional Mixin Path

Include a helper mixin when present; skip it when missing.

SCSS
@use "sass:meta";

@mixin soft-shadow {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

@mixin card($pad: 1rem) {
  @if meta.mixin-exists("soft-shadow") {
    @include soft-shadow;
  }
  padding: $pad;
}

.panel {
  @include card(1.25rem);
}

How It Works

  1. soft-shadow is defined in this file.
  2. mixin-exists returns true.
  3. @include runs on that path.
  4. Remove the mixin and the card still compiles with padding only.

Example 4 — Exists, Then get-mixin + apply

Guard dynamic includes with a boolean check first (Dart Sass 1.69+ for get-mixin / apply).

SCSS
@use "sass:meta";

@mixin elevate {
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.16);
}

$name: "elevate";

.card {
  @if meta.mixin-exists($name) {
    @include meta.apply(meta.get-mixin($name));
  } @else {
    box-shadow: none;
  }
}

How It Works

  1. mixin-exists answers safely for a string name.
  2. get-mixin only runs on the true path.
  3. meta.apply includes the resolved mixin.
  4. Avoids throws from get-mixin on missing names.

Example 5 — Missing Names Return False

Unknown or mistyped names do not throw—they return false.

SCSS
@mixin center {
  display: grid;
  place-items: center;
}
SCSS
@use "sass:meta";
@use "utils";

.flags {
  --nope: #{meta.mixin-exists("definitely-missing")};
  --typo: #{meta.mixin-exists("centerr", $module: "utils")};
  --ok: #{meta.mixin-exists("center", $module: "utils")};
}

How It Works

  1. Unknown names return false.
  2. Typos fail closed (no throw).
  3. Correct spelling in the module returns true.
  4. Safe for optional plugin-style mixins.

Edge Cases & Pitfalls

Most mixin-exists bugs are forgetting $module or confusing it with get-mixin.

module

Namespaced mixins need $module

A bare check will not see members under a @use namespace.

vs

Exists ≠ include

Use meta.get-mixin + meta.apply (or a normal @include) to emit CSS.

order

Define before you check

Like the official sample, a name is false until the @mixin appears above the check’s evaluation.

legacy

Prefer the module API

Global mixin-exists($name) has no $module. Prefer meta.mixin-exists.

Toolchain

Sass Support

Prefer the module form with current Dart Sass.

APIStatus
meta.mixin-exists()Dart Sass via @use "sass:meta"
Return typeBoolean
Optional $moduleNamespace string or module value
Legacy globalmixin-exists($name) (no $module)

Compile with the Dart Sass CLI.

Remember

Key Takeaways

  • Returns true/false for whether a mixin name is defined.
  • Use $module to check mixins under a @use namespace.
  • Pair with get-mixin / apply for safe dynamic includes.
  • Prefer over feature-exists for mixin detection.

One line: to ask whether a mixin is defined, use meta.mixin-exists($name, $module: null).

Practice

Compile Notes

Practical checklist:

checklist.txt
1. @use "sass:meta"
2. meta.mixin-exists("name") or with $module
3. @if … { @include … } for optional paths
4. Guard get-mixin with exists first
5. Prefer this over deprecated feature-exists

Frequently Asked Questions

meta.mixin-exists($name, $module: null) returns true if a mixin named $name is defined, otherwise false.
When the mixin lives in a @use namespace. $module must match that namespace string—for example meta.mixin-exists("center", $module: "utils") after @use "utils".
mixin-exists only answers yes/no. get-mixin returns the mixin value so you can include it with meta.apply. Use exists first for optional mixin names.
mixin-exists looks for mixins. function-exists looks for functions. Same idea, different member type.
Yes for detecting mixins. Official docs recommend function-exists, mixin-exists, and global-variable-exists instead of the deprecated feature-exists helper.
Yes. mixin-exists($name) is the legacy global form (no $module). Prefer meta.mixin-exists after @use "sass:meta".

Next: Sass meta.module-functions()

Get a map of all functions from a loaded module.

meta.module-functions() →

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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