# Function typeof Determine the type of a variable. Function `typeof` recognizes the following types of objects: Object | Returns | Example ---------------------- | ------------- | ------------------------------------------ null | `'null'` | `math.typeof(null)` number | `'number'` | `math.typeof(3.5)` boolean | `'boolean'` | `math.typeof (true)` string | `'string'` | `math.typeof ('hello world')` Array | `'Array'` | `math.typeof ([1, 2, 3])` Date | `'Date'` | `math.typeof (new Date())` Function | `'Function'` | `math.typeof (function () {})` Object | `'Object'` | `math.typeof ({a: 2, b: 3})` RegExp | `'RegExp'` | `math.typeof (/a regexp/)` undefined | `'undefined'` | `math.typeof(undefined)` math.type.BigNumber | `'BigNumber'` | `math.typeof (math.bignumber('2.3e500'))` math.type.Chain | `'Chain'` | `math.typeof (math.chain(2))` math.type.Complex | `'Complex'` | `math.typeof (math.complex(2, 3))` math.type.Fraction | `'Fraction'` | `math.typeof (math.fraction(1, 3))` math.type.Help | `'Help'` | `math.typeof (math.help('sqrt'))` math.type.Index | `'Index'` | `math.typeof (math.index(1, 3))` math.type.Matrix | `'Matrix'` | `math.typeof (math.matrix([[1,2], [3, 4]]))` math.type.Range | `'Range'` | `math.typeof (math.range(0, 10))` math.type.Unit | `'Unit'` | `math.typeof (math.unit('45 deg'))` ## Syntax ```js math.typeof(x) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `x` | * | The variable for which to test the type. ### Returns Type | Description ---- | ----------- string | Returns the name of the type. Primitive types are lower case, non-primitive types are upper-camel-case. For example 'number', 'string', 'Array', 'Date'. ## Examples ```js math.typeof(3.5); // returns 'number' math.typeof(math.complex('2-4i')); // returns 'Complex' math.typeof(math.unit('45 deg')); // returns 'Unit' math.typeof('hello world'); // returns 'string' ```