Sass Introspection

The introspection functions are rarely used when building a stylesheet. However, they are valuable if something does not work properly - to figure out what's going on: like debugging functions.

The following table lists all introspection functions in Sass:

| Function | Description &amp; Example |
|-------------------|---------------------|
| call(function, arguments...) | Calls a function with arguments, and returns the result. |
| content-exists() | Checks whether the current mixin was passed a @content block. |
| feature-exists(feature) | Checks whether feature is supported by the current Sass implementation. **Example:** `feature-exists("at-error");` Result: `true` |
| function-exists(functionname) | Checks whether the specified function exists. **Example:** `function-exists("nonsense")` Result: `false` |
| get-function(functionname, css: false) | Returns the specified function. If css is true, it returns a plain CSS function instead. |
| global-variable-exists(variablename) | Checks whether the specified global variable exists. **Example:** `variable-exists(a)` Result: `true` |
| inspect(value) | Returns a string representation of value. |
| mixin-exists(mixinname) | Checks whether the specified mixin exists. **Example:** `mixin-exists("important-text")` Result: `true` |
| type-of(value) | Returns the type of value. Can be number, string, color, list, map, bool, null, function, arglist. **Example:** `type-of(15px)` Result: `numbertype-of(#ff0000)` Result: `color` |
| unit(number) | Returns the unit associated with a number. **Example:** `unit(15px)` Result: `px` |
| unitless(number) | Checks whether the specified number has a unit associated with it. **Example:** `unitless(15px)` Result: `falseunitless(15)` Result: `true` |
| variable-exists(variablename) | Checks whether the specified variable exists in the current scope. **Example:** `variable-exists(b)` Result: `true` |