When it comes to Javascript Shells, there’s a long list to choose from, but typically, when I want to play with Javascript, the easiest way is to simply open up a console in Chrome.

Recently, I’ve switched over to using SpiderMonkey’s Javascript shell because it allows me to execute a JS file and then drop into the shell.

Installation:

$ brew install spidermonkey

Vanilla Use Case:

Open up a shell with js command:

$ js
js> var obj = {a: 1};
js> obj;
({a:1})
js>

How to execute a file and then drop into the shell:

Given a file example.js with the following contents:

var a = 42;

Execute the file (-f) and continue in interactive mode (-i):

$ js -f example.js -i
js> a;
42

Check out the docs for a full list of options.