JSFiddle - React, Tailwind, and code Playground

JavaScript

const names = [
  "filename.jpeg",
  "filename-.png",
  "file name.doc",
  "file name 3.mp4",
  "file name -.dxg",
  "file.name.mov"
];

const matches = names.filter(name => 
	name.lastIndexOf("-") 
  	=== name.lastIndexOf(".") - 1);

document.write(matches);