denoland-deno/fs/utils.ts

import * as path from "./path/mod.ts";

/**
 * Test whether or not `dest` is a sub-directory of `src`
 * @param src src file path
 * @param dest dest file path
 * @param sep path separator
 */
export function isSubdir(
  src: string,
  dest: string,
  sep: string = path.sep
): boolean {
  if (src === dest) {
    return false;
  }
  const srcArray = src.split(sep);
  const destArray = dest.split(sep);

  return srcArray.reduce((acc, current, i) => {
    return acc && destArray[i] === current;
  }, true);
}