Nov 1, 2022

Find duplicate code between two folders in a project

A CLI tool to quickly identify duplicate code.

I needed to identify common code between 2 folders of the same project.

Instead of checking all the files manually one by one, I used a tool that made the task easier: jscpd.

It's an NPM package that you can install in your project, but in my case I used the CLI version.

If I want to find the code in common between the ./folder1 and ./folder2 folders in my next.js project, want to ignore the code compiled in ./.next and the ./node_modules, and want an html report, I position myself at the root of my project, and run the following command:

npx jscpd --skipLocal ./folder1 ./folder2 --reporters html --ignore "**/node_modules,**/.next"

Then you just have to open the file ./report/html/index.html in a browser to see the report.

Settings#

We can also change the basic parameters according to our needs. The documentation lists all the options.

For example, if we take the following command line:

npx jscpd --pattern "src/**/*.js" --min-tokens 15 --min-lines 5

• --pattern or -p allows us to target only the files corresponding to a given pattern. Here we will target all javascript files in the src folder.
• --min-tokens or -k is the minimum number of token repetitions. A token is the equivalent of a word. Here, an extract of code will only be detected as duplicated if it has 15 or more identical tokens.
• --min-lines or -l is the minimum number of lines of code to detect. Here, an extract of code will be detected as duplicated only from 15 identical lines.

Source