NOTE: The package what-is was renamed to wots. Please, consider installing the renamed version.

why?

The library was written as a simple coding exercise, but then appeared useful to share :wink:

how?

npm install --save what-is

and then

var whatis = require('what-is');

// ...

if (whatis(myNotAlwaysNumericVariable) === 'NaN') {
    // do some stuff
}

what?

whatis() function returns reasonable type names for tested values:

| description | input | result | | :------------------ | :---------------------------------- |:------------- | | null | null | 'null' | | undefined | undefined | 'undefined' | | strings | 'foo' | 'string' | | | '' | 'string' | | | ['Hello', 'world!'].join(' ') | 'string' | | | new String() | 'string' | | numbers | 5 | 'number' | | | parseInt(42) | 'number' | | | new Number('3') | 'number' | | | NaN | 'NaN' | | | Infinity | 'Infinity' | | | 1 / -0 | 'Infinity' | | boolean values | false | 'boolean' | | | !!nonEmptyVariable | 'boolean' | | |new Boolean('0') | 'boolean' | | regular expressions | /^test$/g | 'regexp' | | | new RegExp('needle', 'i') | 'regexp' | | arrays | ['foo', 'bar', 'baz'] | 'array' | | | new Array(10) | 'array' | | objects | { foo: 'bar'} | 'object' | | | {} | 'object' | | | new Object() | 'object' | | | Object.create(null) | throws error (to be fixed) | | functions | function () {} | 'function' | | | new Function('return null') | 'function' | | date objects | new Date() | 'date' | | errors | new Error('error!') | 'error' | | | new TypeError('type error!') | 'error' | | arguments objects | (function(){return arguments;})() | 'arguments' | | class constructors | new MyClass() | 'myclass' | | | new Buffer() | 'buffer' | | | new XMLHttpRequest() | 'xmlhttprequest' | | promises | new Promise(function() {}) | 'promise' | | | Promise.resolve('data') | 'promise' | | | Promise.reject(new Error('Oop!')) | 'promise' |

Note: for more examples see test file