jsPerf.app is an online JavaScript performance benchmark test runner & jsperf.com mirror. It is a complete rewrite in homage to the once excellent jsperf.com now with hopefully a more modern & maintainable codebase.

jsperf.com URLs are mirrored at the same path, e.g:

https://jsperf.com/negative-modulo/2

Can be accessed at:

https://jsperf.app/negative-modulo/2

obscure typeof vs straightforward typeof - false test

Benchmark created by T.J. Crowder on October 25, 2013

Description

Tests the difference in performance between the obscure ({"function":1}[typeof somefunc]) way of testing if something is a function vs the straightforward (typeof somefunc=="function"). Using the version with quotes to work around a bug in IE.

This is the test for when the result is false.

Setup

function somefunc() {}
    var functionTester = {"function":1};

Test runner

Ready to run.

Testing in
Test		Ops/sec
Obscure inline	`if ({"function":1}[typeof foo]) throw "Error";`	ready
Obscure cached	`if (functionTester[typeof foo]) throw "Error";`	ready
Straightforward	`if (typeof foo=="function") throw "Error";`	ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

Revision 1: published by T.J. Crowder on October 25, 2013