**Karma** is a tool that spawns a web server that executes source code against test code for each of the connected browsers. Karma watches all the files specified in the configuration file. The test run is triggered when a file is changed, and browsers are informed about rerunning the test code. Hence, Karma belongs to the *Browser Testing* category. 

The test results are shown on the command line, and the developer can easily examine the tests which failed and passed. 

Karma is not a testing framework. It simply generates the test runner HTML file. 

> [Click here](http://karma-runner.github.io/6.3/intro/how-it-works.html) for more information about how Karma is configured and how it works. 

Some important features of Karma include the following:

A **testing framework** is an environment that allows the developer to run the tests and display the results. **Mocha** is a Javascript testing framework that runs on node.js and browsers. It runs serially, which allows asynchronous testing to be flexible and accurate. Unlike Karma which is a browser testing tool, Mocha is categorized as *Javascript Testing Framework*. 

> [Click here](https://mochajs.org) to find out more about Mocha installation and how it works. 

Some key features of Mocha include the following:

**Jasmine** is a behavior-driven development framework that tests Javascript code. Jasmine does not depend on any other Javascript frameworks and does not require a DOM. Jasmine is best suited for node.js projects, websites, and any Javascript code.  

> [Click here](https://jasmine.github.io) to find out more information about Jasmine's installation and setup. 

Some key features of Jasmine include the following:

# Comparison
Jasmine includes both an assertion library and a testing framework. An **assertion library** is a syntax written by the developers themselves to test out a code. 

On the other hand, Mocha does not include an assertion library giving the developer a choice to choose one according to their preference. 

Karma does not have a standalone configuration. One can use it with any testing framework or assertion library. The key feature of Karma is that it can test node.js projects in browsers. Karma is often used together with a testing framework (either Jasmine or Mocha) for unit testing. 

Mocha vs Karma vs Jasmine. What to use when?

Karma spawns web servers for browser tests; Mocha is a flexible testing framework, while Jasmine is behavior-driven and independent of other JS frameworks.