How can I modify the source code and apply it?

[smart4654154]

Thank you very much for your work
I have downloaded your source code and I would like to modify it. For example, I modified gsplat.js-main \ src \ cameras \ CameraData.ts
The private _fx: number = 1132;  private _fx: number = 532;
Then, create this case

As a beginner, I am not familiar with web development. Can you teach me? I hope my modifications can be viewed on the webpage（ http://localhost:5173/ ）Immediately and automatically generate corresponding changes
Thank you very much.