diff --git a/LEEME.md b/LEEME.md
index 3d9ea8a..15bd716 100644
--- a/LEEME.md
+++ b/LEEME.md
@@ -66,9 +66,17 @@ En caso de recibir como parámetro `coalesce.throwError(message)`
 y que los parámetros anteriores no están definidos o son distintos de null
 lanza una excepción con ese mensaje. 
 
+En caso de recibir como parámetro `coalesce.throwErrorIfUndefined(message)` 
+y que los parámetros anteriores no están definidos 
+lanza una excepción con ese mensaje. 
+
 <!--lang:en--]
 
-Returns the first not null nor undefined parameter
+Returns the first not null nor undefined parameter. 
+
+Use `coalesce.throwError(message)` for throw an Exception if all parameters are null or undefined.
+
+Use `coalesce.throwErrorIfUndefined(message)` for throw an Exception if all parameters are undefined.
 
 [!--lang:*-->
 
diff --git a/best-globals.js b/best-globals.js
index 71b7815..650d70b 100644
--- a/best-globals.js
+++ b/best-globals.js
@@ -28,13 +28,25 @@ var bestGlobals = {};
 
 bestGlobals.coalesce=function coalesce(){
     var i=0;
-    while(i<arguments.length-1 && arguments[i]==null){
+    var hasNull=false;
+    while(i<arguments.length && arguments[i]==null){
+        hasNull=hasNull || arguments[i]===null;
         i++;
     }
     if(arguments[i] instanceof bestGlobals.coalesce.throwError){
-        throw new Error(arguments[i].message);
+        if(arguments[i] instanceof bestGlobals.coalesce.throwErrorIfUndefined && hasNull){
+            return null;
+        }else{
+            throw new Error(arguments[i].message);
+        }
+    }
+    if(i>=arguments.length){
+        if(hasNull){
+            return null;
+        }
+    }else{
+        return arguments[i];
     }
-    return arguments[i];
 };
 
 bestGlobals.coalesce.throwError=function throwError(message){
@@ -45,6 +57,16 @@ bestGlobals.coalesce.throwError=function throwError(message){
     }
 };
 
+bestGlobals.coalesce.throwErrorIfUndefined=function throwErrorIfUndefined(message){
+    if(this === bestGlobals.coalesce){
+        return new bestGlobals.coalesce.throwErrorIfUndefined(message);
+    }else{
+        this.message=message;
+    }
+}
+
+bestGlobals.coalesce.throwErrorIfUndefined.prototype=Object.create(bestGlobals.coalesce.throwError.prototype);
+
 function retreiveOptions(functionCallee, functionAruguments, mandatoryPositionCountingFromOne){
     if(functionAruguments.length<mandatoryPositionCountingFromOne){
         return {};
diff --git a/package.json b/package.json
index 65853ed..1352c40 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "best-globals",
   "description": "common global function and constants - i.e. coalesce",
-  "version": "0.4.5",
+  "version": "0.4.6",
   "author": "Codenautas <codenautas@googlegroups.com>",
   "license": "MIT",
   "repository": "codenautas/best-globals",
diff --git a/test/test.js b/test/test.js
index 5cc0363..cf7dd6b 100644
--- a/test/test.js
+++ b/test/test.js
@@ -10,18 +10,34 @@ describe('best-globals', function(){
         it('return the first value if is not null',function(){
             expect(bestGlobals.coalesce(7,8)).to.be(7);
             expect(bestGlobals.coalesce(7,8,bestGlobals.coalesce.throwError)).to.be(7);
+            expect(bestGlobals.coalesce(7,8,bestGlobals.coalesce.throwErrorIfUndefined)).to.be(7);
         });
         it('return the first not null value',function(){
             expect(bestGlobals.coalesce(null,null,null,null,null,null,null,null,null,null,null,null,null,17,8)).to.be(17);
             expect(bestGlobals.coalesce(null,null,null,null,null,null,null,null,null,null,null,null,null,17,8,bestGlobals.coalesce.throwError)).to.be(17);
+            expect(bestGlobals.coalesce(null,null,null,null,null,null,null,null,null,null,null,null,null,17,8,bestGlobals.coalesce.throwErrorIfUndefined)).to.be(17);
         });
-        it('return the last value if all are nulls',function(){
-            expect(typeof bestGlobals.coalesce(null,{}.inex)).to.be("undefined");
+        it('coalesce(null,undefined)===null',function(){
+            expect(bestGlobals.coalesce(null,{}.inex)+"").to.be("null");
+        });
+        it('coalesce(undefined,undefined)===undefined',function(){
+            expect(typeof bestGlobals.coalesce(undefined,{}.inex)).to.be("undefined");
         });
         it('throw error if all are nulls',function(){
             expect(function(){
-                typeof bestGlobals.coalesce(null,{}.inex,bestGlobals.coalesce.throwError("this message"));
+                typeof bestGlobals.coalesce(null,null,bestGlobals.coalesce.throwError("this message"));
             }).to.throwError(/this message/);
+            expect(
+                bestGlobals.coalesce(null,null,bestGlobals.coalesce.throwErrorIfUndefined("m2"))+""
+            ).to.eql("null");
+        });
+        it('throw error if all are undefined',function(){
+            expect(function(x){
+                bestGlobals.coalesce({}.inex,undefined,x,bestGlobals.coalesce.throwError("msgE"))
+            }).to.throwError(/msgE/);
+            expect(function(x){
+                typeof bestGlobals.coalesce(x,undefined,{}.inex,bestGlobals.coalesce.throwErrorIfUndefined("msgU"));
+            }).to.throwError(/msgU/);
         });
         var valids=[
             { element:[]         },