To Path Case

function toPathCase(str) {
  return str
    .replace(/^[^A-Za-z0-9]*|[^A-Za-z0-9]*$/g, "")
    .replace(/([a-z])([A-Z])/g, (m, a, b) => `${a}_${b.toLowerCase()}`)
    .replace(/[^A-Za-z0-9]+|_+/g, "/")
    .toLowerCase();
}

toPathCase("hello world"); // "hello/world"