1 files changed, 84 insertions, 0 deletions
diff --git a/challenge-002/abigail/node/ch-2.js b/challenge-002/abigail/node/ch-2.js
new file mode 100644
index 0000000000..84d0f6976e
--- /dev/null
+++ b/challenge-002/abigail/node/ch-2.js
@@ -0,0 +1,84 @@
+#!/usr/local/bin/node
+
+//
+// See ../README.md
+//
+
+//
+// Run as: node ch-2.js {-f | -t} < input-file
+//
+//   -f: Translate from base 35 to base 10
+//   -t: Translate to base 35 from base 10
+//
+
+let BASE = 35
+
+//
+// Parse options using the yargs module
+//
+const argv = require ('yargs')
+. option ('from_base', {
+    alias: 'f',
+    type:  'boolean',
+})
+. option ('to_base', {
+    alias: 't',
+    type:  'boolean',
+})
+. argv;
+
+//
+// Check options
+//
+if ((argv . to_base ? 1 : 0) + (argv . from_base ? 1 : 0) != 1) {
+    console . log ("Requires exactly one of '-f' or '-t'")
+    process . exit (1)
+}
+
+//
+// Set up digits, mapping base-10 numbers to base-35 digits, and vice versa
+//
+let digits = {};
+for (let i = 0; i < 10; i ++) {
+    digits [i] = i
+}
+for (let i = 10; i < BASE; i ++) {
+    let char = String . fromCharCode (65 + i - 10)
+    digits [char] = i
+    digits [i] = char
+}
+
+//
+// Translate to base 35
+//
+function to_base (number) {
+    let out = "";
+    while (number) {
+        let n = number % BASE
+        out = digits [n] + out
+        number = Math . floor (number / BASE)
+    }
+    return out
+}
+
+//
+// Translate from base 35
+//
+function from_base (base) {
+    let out = 0
+    base . split ('') . forEach (c => {
+        out = BASE * out + digits [c]
+    })
+    return out
+}
+
+
+//
+// Iterate over the input, call either to_base or from_base for each
+// line, depending on the -f or -t parameter.
+//
+require ('readline')
+. createInterface ({input: process . stdin})   
+. on ('line', _ => console . log (argv . to_base ? to_base (+ _)
+                                                 : from_base (_ . trim ())))
+;