fix for issue #163

Author: peterolson

BigInteger.js

@@ -986,15 +986,14 @@ var bigInt = (function (undefined) {
     var powers2Length = powersOfTwo.length, highestPower2 = powersOfTwo[powers2Length - 1];
 
     function shift_isSmall(n) {
-        return ((typeof n === "number" || typeof n === "string") && +Math.abs(n) <= BASE) ||
-            (n instanceof BigInteger && n.value.length <= 1);
+        return Math.abs(n) <= BASE;
     }
 
-    BigInteger.prototype.shiftLeft = function (n) {
+    BigInteger.prototype.shiftLeft = function (v) {
+        var n = parseValue(v).toJSNumber();
         if (!shift_isSmall(n)) {
             throw new Error(String(n) + " is too large for shifting.");
         }
-        n = +n;
         if (n < 0) return this.shiftRight(-n);
         var result = this;
         if (result.isZero()) return result;
@@ -1006,12 +1005,12 @@ var bigInt = (function (undefined) {
     };
     NativeBigInt.prototype.shiftLeft = SmallInteger.prototype.shiftLeft = BigInteger.prototype.shiftLeft;
 
-    BigInteger.prototype.shiftRight = function (n) {
+    BigInteger.prototype.shiftRight = function (v) {
         var remQuo;
+        var n = parseValue(v).toJSNumber();
         if (!shift_isSmall(n)) {
             throw new Error(String(n) + " is too large for shifting.");
         }
-        n = +n;
         if (n < 0) return this.shiftLeft(-n);
         var result = this;
         while (n >= powers2Length) {