How can I measure the execution time of a npm/yarn task/script?

Question

How can I measure the execution time of a npm/yarn task on the command line without modifying the scripts.

In my special use case I want to execute an existing E2E-Test (yarn test:e2e) 100 times and take the average value.

Answer 1

You could use the npm package gnomon:

A command line utility, a bit like moreutils's ts, to prepend timestamp information to the standard output of another command.

Install it like this:

$ npm i -g gnomon

With this you could run:

$ yarn install | gnomon

And it might give you an output like this:

$ yarn install | gnomon 
   0.5327s   yarn install v1.9.4
   1.9652s   [1/4] Resolving packages...
   0.0160s   success Already up-to-date.
   0.0163s   Done in 2.38s.
   0.0003s   

     Total   2.5315s