This repo is using D3.js as a library to create SVG visuals.
You can find the latest version by file name followed by latest version number, example: scotterPlot31
Script is a file that using D3.js to create SVG visualizations that interact with Local Data Source only. Means you need to add the data object manaually as JSON file or object. script.js is been called from index.html to display the page locally without any server.
Is the same code as script.js but this file contains a structure that could work for Looker only, means you will not be able to see the visual locally.
You can notice the structure start with updateAsync function and ended with doneRendering() function. Please follow the steps in the custom visualizations from looker
Inside the updateAsync function you will be able to use and access the properties of data and queryResponse to determine how your visual should act and what to display in the visualization based on real looker data.