Tutorials

Sass feature-exists() Function

Posted in Sass Tutorial

Updated on Sep 30, 2024

By Mari Selvan

👁️ 23 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

The feature-exists() function in Sass is used to check if a particular feature is available in the current Sass implementation.

This function is particularly useful when writing cross-version compatible code or when you want to ensure that certain features are available before using them in your stylesheets.

💡 Syntax

The syntax of the feature-exists() function is simple and straightforward. It takes one argument, which is the name of the feature you want to check for.

Syntax

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feature-exists($feature-name)

🔢 Parameters

$feature-name: The name of the feature you wish to check. This is a string and should be the exact name of the feature as recognized by Sass.

↩️ Return Value

The function returns a Boolean value:

true: if the feature is available.
false: if the feature is not available.

🌟 Common Features to Check

Some commonly checked features include:

"global-variable-shadowing": Checks if global variable shadowing is supported.
"at-error": Checks if the @error directive is supported.
"units-level-3": Checks if level 3 units are supported.
"custom-properties": Checks if CSS custom properties (variables) are supported.

📝 Example Usage

Let’s explore some practical examples of how to use feature-exists() in your Sass projects.

📜 Example 1: Basic Feature Check

example.scss

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@if feature-exists("global-variable-shadowing") {
  $color: blue;
  @debug "Global variable shadowing is supported.";
} else {
  @debug "Global variable shadowing is not supported.";
}

In this example, the code checks if the "global-variable-shadowing" feature is supported in the current Sass environment and outputs a debug message accordingly.

📜 Example 2: Conditionally Using Features

example.scss

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$use-new-feature: false;

@if feature-exists("at-error") {
  $use-new-feature: true;
}

@if $use-new-feature {
  @error "This is a custom error message.";
} else {
  @warn "The @error directive is not supported.";
}

This example demonstrates how you can conditionally use a feature based on its availability. If the @error directive is supported, it will be used; otherwise, a warning is issued.

📜 Example 3: Checking for Units-Level-3 Support

example.scss

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@if feature-exists("units-level-3") {
  $spacing: 1rem;
} else {
  $spacing: 16px;
}

.container {
  margin: $spacing;
}

Here, the code checks if level 3 units are supported. If they are, it uses rem units; otherwise, it falls back to px.

🎉 Conclusion

The feature-exists() function in Sass is a powerful tool for ensuring compatibility and making your stylesheets more robust. By using this function, you can write conditional code that adapts to the capabilities of the current Sass environment, avoiding potential errors or unsupported features.

This function is particularly useful in larger projects or libraries where you want to maintain compatibility across different Sass versions or implementations. By leveraging feature-exists(), you can enhance the reliability and flexibility of your Sass code, ensuring it works seamlessly across various environments.