const files = [ 'foo.txt ', '.bar', '   ', 'baz.foo' ];
let filePaths = [];

for (let file of files) {
  const fileName = file.trim();
  if(fileName) {
    const filePath = `~/cool_app/${fileName}`;
    filePaths.push(filePath);
  }
}

// filePaths = [ '~/cool_app/foo.txt', '~/cool_app/.bar', '~/cool_app/baz.foo']