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The fastest JavaScript type checker for V8

NPM version Build Status Coverage Status

Why tipe?

JavaScript's native typeof is famously broken. Many folks turn to the excellent is library for help:

Not content with is? You should probably write your own type checker. Still not content? Tipe has been hand-tuned to provide the fastest internal test possible for any type expression on the V8 Javascript engine. This makes it particularly well suited for highly-scalable node.js applications.

Install with nodejs

    npm install tipe

Basic use

Tipe includes a base method, tipe(value) which always returns a string, like typeof, for all valid identifiers, including custom tipes. This is useful in switch statements.

var tipe = require('tipe')
tipe()              // 'undefined' 
tipe(null)          // 'null' 
tipe('foo')         // 'string' 
tipe(false)         // 'boolean' 
tipe(1)             // 'number' 
tipe({})            // 'object' 
tipe([])            // 'array' 
tipe(new Error())   // 'error' 
var args, fn
fn = function(){args = arguments}
tipe(fn)            // 'function' 
tipe(args)          // 'arguments' 

Boolean test methods for each type

For each tipe there are two boolean test methods: tipe.tipename(value), and tipe.isTipename(value). Some prefer the shorter version, others perfer methods names that are not reserved words.

tipe.boolean(false)       // true 
tipe.isBoolean(false)     // true 
tipe.error(new Error())   // true 
tipe.isError(new Error()) // true 

etc... These appear automatically for custom types as well.

Custom Types

Tipe lets you add your own custom types for any constructor. They work like any other type.

function Dog(){}
var fido = new Dog()
tipe(fido)              // 'object'          // runtime exception: tipe has no method 'dog' 
tipe.addTipe('Dog', 'dog')
tipe(fido)              // 'dog'          // true 
tipe.isDog(fido)        // true 


Tipe aims to be as fast as any pure javascript type checker can be. For each internal type check, tipe chooses the fastest availble V8 expression to determine the result. To see method-by-method comparisons for yourself, run:

node bench

Here is the bench summary output for tipe@0.1.12 vs is@2.2.0, weighing shared methods equally:

benchmarking /Users/gs/tipe/bench.js
Please be patient.
{ http_parser: '1.0',
  node: '0.10.33',
  v8: '',
  ares: '1.9.0-DEV',
  uv: '0.10.29',
  zlib: '1.2.3',
  modules: '11',
  openssl: '1.0.1j' }
Scores: (bigger is better)
 > 126.62013958125623
 > 125.62313060817547
 > 126.74650698602794
 > 126.74650698602794
 > 126.49402390438247
 > 127.49003984063745
 > 126.87312687312688
 > 126.74650698602794
Average (mean) 126.6674977207078
 > 55.94405594405595
 > 55.83250249252243
 > 55.99214145383104
 > 55.83250249252243
 > 56.32411067193676
 > 56.26850937808489
 > 56.21301775147929
 > 56.10236220472441
Average (mean) 56.063650298644646
Winner: tipe
Compared with next highest (is), it's:
55.74% faster
2.26 times as fast
0.35 order(s) of magnitude faster


3meters relies on the public tipe module for our aircandi web service.


We welcome any improvements via email, issues, or PRs.


Copyright (c) 2013 3meters. All rights reserverd.