feat(std/node) add CommonJS require (#3380)

1 files changed, 52 insertions, 0 deletions

diff --git a/std/node/tests/node_modules/left-pad/index.js b/std/node/tests/node_modules/left-pad/index.js
new file mode 100644
index 000000000..e90aec35d
--- /dev/null
+++ b/std/node/tests/node_modules/left-pad/index.js
@@ -0,0 +1,52 @@
+/* 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;
+}