Another take at pre-compilation, which doesn't use eval.

Author: hildjj

jsonpointer.js

@@ -1,28 +1,12 @@
 var console = require("console");
 
 var untilde = function(str) {
-  return str.replace(/(~.)|[\b\f\n\r\t\v\\']/g, function(m) {
+  return str.replace(/~./g, function(m) {
     switch (m) {
       case "~0":
         return "~";
       case "~1":
         return "/";
-      case "'":
-        return "\\'";
-      case "\b":
-        return "\\b";
-      case "\f":
-        return "\\f";
-      case "\n":
-        return "\\n";
-      case "\r":
-        return "\\r";
-      case "\t":
-        return "\\t";
-      case "\v":
-        return "\\v";
-      case "\\":
-        return "\\\\";
     }
     throw("Invalid tilde escape: " + m);
   });
@@ -43,30 +27,38 @@ var compile = function(pointer) {
     }
   }
 
-  var fn = "";
-  var part;
-  var len = pointer.length - 1;
-  if (len < 0) {
-    fn += "if (typeof value !== 'undefined') { throw(new Error('Invalid JSON pointer for set.')); }\n";
-  } else {
-    for (var i=0; i<len; i++) {
-      part = untilde(pointer[i]);
-      fn += "if (!obj) { return null; }\n";
-      fn += "obj = obj['" + part + "'];\n"
+  var len = pointer.length;
+  if (len === 0) {
+    return function(obj, value) {
+      if (typeof value !== 'undefined') {
+        throw(new Error('Invalid JSON pointer for set.'));
+      }
+      return obj;
     }
-    part = untilde(pointer[len]);
-    fn += "if (!obj) { return null; }\n";
-    fn += "if (typeof value !== 'undefined') {\n" +
-          "  var old_value = obj['" + part + "'];\n" +
-          "  obj['" + part + "'] = value;\n" +
-          "  obj = old_value;\n" +
-          "} else {\n" +
-          "  obj = obj['" + part + "'];\n" +
-          "}\n";
   }
 
-  fn += "return obj;\n"
-  return new Function("obj", "value", fn);
+  pointer = pointer.map(untilde);
+
+  return function(obj, value) {
+    var parent = null;
+    var part = null;
+    for (var i=0; i<len; i++) {
+      if (!obj) {
+        if (typeof value !== 'undefined') {
+          throw new Error("Path not found for set");
+        }
+        return null;
+      }
+      parent = obj;
+      part = pointer[i];
+      obj = obj[part];
+    }
+
+    if (typeof value !== 'undefined') {
+      parent[part] = value;
+    }
+    return obj;
+  }
 }
 
 var get = function(obj, pointer) {