How to run Javascript

Question

I have a working Gulp script that I use to create my SVG sprites along with a preview page. But now I want to enrich the preview page, more precisely each icon in it, with information that I have in a separate json file. But I don't have any idea how to do this.

It should look something like this:

function taskFactory(name, spriteMode) {
    return gulp.src(srcSvgDir + '*.svg')
        .pipe(svgSprite(config))
        .pipe(jeditor((json) => {
                
    // read json file for this sprite
    // iterate entries in json
    // Find the location in preview page (by selector or placeholder string) and paste the information from the json entry. 

    }))
    .pipe(gulp.dest(destDir));
}

But I have no idea if I even have access to this preview page that is being created. If anyone has a completely different idea, I'm open to anything.

In a case of emergency, I could write a C# console app that, after creating the sprite and preview page, parses and edits the latter file. I don't think that's so nice though, since I want to create it purely with Gulp.