added primes

primes.js

@@ -0,0 +1,31 @@
+const compare_positive = require("./compare_positive.js");
+const divide = require("./divide.js");
+const is_integer = require("./is_integer.js");
+const long_addition = require("./long_addition.js");
+
+/**
+ *
+ * @param {String} start - numerical string
+ * @param {String} end - numerical end
+ * @returns {Array.<string>} primes - array of prime numbers as strings
+ */
+function primes(start = "0", end = "100") {
+  const prime_single_digits = ["2", "3", "5", "7", "11"];
+  const results = prime_single_digits.filter(n => compare_positive(n, start) !== "<" && compare_positive(n, end) !== ">");
+
+  let num = "13";
+
+  while (compare_positive(num, end) !== ">") {
+    // don't even bother checking if ends with 5 or all one number
+    if (!(/^\d+5/.test(num) || /^(\d)\1+/.test(num))) {
+      if (["9", "7", "3"].every(digit => !is_integer(divide(num, digit)))) {
+        results.push(num);
+      }
+    }
+    num = long_addition(num, "2");
+  }
+  return results;
+}
+
+module.exports = primes;
+module.exports.default = primes;