feat: add ext/node for require support (#15362)

This commit adds "ext/node" extension that implementes CommonJS module system.

In the future this extension might be extended to actually contain implementation of
Node compatibility layer in favor of "deno_std/node".

Currently this functionality is not publicly exposed, it is available via "Deno[Deno.internal].require"
namespace and is meant to be used by other functionality to be landed soon.

This is a minimal first pass, things that still don't work:

support for dynamic imports in CJS
conditional exports

1 files changed, 54 insertions, 0 deletions

diff --git a/cli/tests/testdata/commonjs/node_modules/left-pad/index.js b/cli/tests/testdata/commonjs/node_modules/left-pad/index.js
new file mode 100644
index 000000000..a439e91de
--- /dev/null
+++ b/cli/tests/testdata/commonjs/node_modules/left-pad/index.js
@@ -0,0 +1,54 @@
+// deno-lint-ignore-file
+
+/* This program is free software. It comes without any warranty, to
+     * the extent permitted by applicable law. You can redistribute it
+     * and/or modify it under the terms of the Do What The Fuck You Want
+     * To Public License, Version 2, as published by Sam Hocevar. See
+     * http://www.wtfpl.net/ for more details. */
+"use strict";
+module.exports = leftPad;
+
+var cache = [
+  "",
+  " ",
+  "  ",
+  "   ",
+  "    ",
+  "     ",
+  "      ",
+  "       ",
+  "        ",
+  "         ",
+];
+
+function leftPad(str, len, ch) {
+  // convert `str` to a `string`
+  str = str + "";
+  // `len` is the `pad`'s length now
+  len = len - str.length;
+  // doesn't need to pad
+  if (len <= 0) return str;
+  // `ch` defaults to `' '`
+  if (!ch && ch !== 0) ch = " ";
+  // convert `ch` to a `string` cuz it could be a number
+  ch = ch + "";
+  // cache common use cases
+  if (ch === " " && len < 10) return cache[len] + str;
+  // `pad` starts with an empty string
+  var pad = "";
+  // loop
+  while (true) {
+    // add `ch` to `pad` if `len` is odd
+    if (len & 1) pad += ch;
+    // divide `len` by 2, ditch the remainder
+    len >>= 1;
+    // "double" the `ch` so this operation count grows logarithmically on `len`
+    // each time `ch` is "doubled", the `len` would need to be "doubled" too
+    // similar to finding a value in binary search tree, hence O(log(n))
+    if (len) ch += ch;
+    // `len` is 0, exit the loop
+    else break;
+  }
+  // pad `str`!
+  return pad + str;
+}