mathjs/docs/reference/functions/typeOf.md

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# 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.BigNumber         | `'BigNumber'` | `math.typeOf(math.bignumber('2.3e500'))`
math.Chain             | `'Chain'`     | `math.typeOf(math.chain(2))`
math.Complex           | `'Complex'`   | `math.typeOf(math.complex(2, 3))`
math.Fraction          | `'Fraction'`  | `math.typeOf(math.fraction(1, 3))`
math.Help              | `'Help'`      | `math.typeOf(math.help('sqrt'))`
math.Help              | `'Help'`      | `math.typeOf(math.help('sqrt'))`
math.Index             | `'Index'`     | `math.typeOf(math.index(1, 3))`
math.Matrix            | `'Matrix'`    | `math.typeOf(math.matrix([[1,2], [3, 4]]))`
math.Range             | `'Range'`     | `math.typeOf(math.range(0, 10))`
math.ResultSet         | `'ResultSet'` | `math.typeOf(math.evaluate('a=2\nb=3'))`
math.Unit              | `'Unit'`      | `math.typeOf(math.unit('45 deg'))`
math.AccessorNode            | `'AccessorNode'`            | `math.typeOf(math.parse('A[2]'))`
math.ArrayNode               | `'ArrayNode'`               | `math.typeOf(math.parse('[1,2,3]'))`
math.AssignmentNode          | `'AssignmentNode'`          | `math.typeOf(math.parse('x=2'))`
math.BlockNode               | `'BlockNode'`               | `math.typeOf(math.parse('a=2; b=3'))`
math.ConditionalNode         | `'ConditionalNode'`         | `math.typeOf(math.parse('x<0 ? -x : x'))`
math.ConstantNode            | `'ConstantNode'`            | `math.typeOf(math.parse('2.3'))`
math.FunctionAssignmentNode  | `'FunctionAssignmentNode'`  | `math.typeOf(math.parse('f(x)=x^2'))`
math.FunctionNode            | `'FunctionNode'`            | `math.typeOf(math.parse('sqrt(4)'))`
math.IndexNode               | `'IndexNode'`               | `math.typeOf(math.parse('A[2]').index)`
math.ObjectNode              | `'ObjectNode'`              | `math.typeOf(math.parse('{a:2}'))`
math.ParenthesisNode         | `'ParenthesisNode'`         | `math.typeOf(math.parse('(2+3)'))`
math.RangeNode               | `'RangeNode'`               | `math.typeOf(math.parse('1:10'))`
math.SymbolNode              | `'SymbolNode'`              | `math.typeOf(math.parse('x'))`


## 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'
```