Squashed commit of the following:

commit c373ac4
Author: Danny Wang <wangyang0123@gmail.com>
Date:   Tue Apr 10 12:38:13 2012 +0800

    moved i and l delarations to the top of page.evaluate()

commit bf24d4d
Author: Danny Wang <wangyang0123@gmail.com>
Date:   Tue Apr 10 08:54:55 2012 +0800

    fixed defects in evaluate() pointed out by detro

commit 0bb8cff
Author: Danny Wang <wangyang0123@gmail.com>
Date:   Fri Apr 6 19:21:47 2012 +0800

    added passing variables to function for page.evaluate

    http://code.google.com/p/phantomjs/issues/detail?id=132

src/modules/webpage.js

@@ -187,6 +187,30 @@ exports.create = function (opts) {
         this._appendScriptElement(scriptUrl);
     };
 
+    /**
+     * evaluate a function in the page
+     * @param   {function}  func    the function to evaluate
+     * @param   {...}       args    function arguments
+     * @return  {*}                 the function call result
+     */
+    page.evaluate = function (func, args) {
+        var str, arg, i, l;
+        if (!(func instanceof Function || typeof func === 'string' || func instanceof String)) {
+            throw "Wrong use of WebPage#evaluate";
+        }
+        str = 'function() { return (' + func.toString() + ')(';
+        for (i = 1, l = arguments.length; i < l; i++) {
+            arg = arguments[i];
+            if (/object|string/.test(typeof arg) && !(arg instanceof RegExp)) {
+                str += 'JSON.parse(' + JSON.stringify(JSON.stringify(arg)) + '),';
+            } else {
+                str += arg + ',';
+            }
+        }
+        str = str.replace(/,$/, '') + '); }';
+        return this.evaluateJavaScript(str);
+    }
+
     // Copy options into page
     if (opts) {
         page = copyInto(page, opts);

src/webpage.cpp

@@ -291,7 +291,7 @@ QVariantMap WebPage::paperSize() const
     return m_paperSize;
 }
 
-QVariant WebPage::evaluate(const QString &code)
+QVariant WebPage::evaluateJavaScript(const QString &code)
 {
     QString function = "(" + code + ")()";
     return m_mainFrame->evaluateJavaScript(function, QString("phantomjs://webpage.evaluate()"));

src/webpage.h

@@ -89,7 +89,7 @@ public slots:
     void openUrl(const QString &address, const QVariant &op, const QVariantMap &settings);
     void release();
 
-    QVariant evaluate(const QString &code);
+    QVariant evaluateJavaScript(const QString &code);
     bool render(const QString &fileName);
     bool injectJs(const QString &jsFilePath);
     void _appendScriptElement(const QString &scriptUrl);

test/webpage-spec.js

@@ -323,6 +323,65 @@ describe("WebPage object", function() {
         });
 
     });
+
+    it("should pass variables to functions properly", function() {
+        var testPrimitiveArgs = function() {
+            var samples = [
+                true,
+                0,
+                "`~!@#$%^&*()_+-=[]\{}|;':\",./<>?",
+                undefined,
+                null
+            ];
+            for (var i = 0; i < samples.length; i++) {
+                if (samples[i] !== arguments[i]) {
+                    console.log("FAIL");
+                }
+            }
+        };
+
+        var testComplexArgs = function() {
+            var samples = [
+                {a:true, b:0, c:"string"},
+                function() { return true; },
+                [true, 0, "string"],
+                /\d+\w*\//
+            ];
+            for (var i = 0; i < samples.length; i++) {
+                if (typeof samples[i] !== typeof arguments[i] 
+                    || samples[i].toString() !== arguments[i].toString()) {
+                    console.log("FAIL");
+                }
+            }
+        };
+
+        var message;
+        runs(function() {
+            page.onConsoleMessage = function (msg) {
+                message = msg;
+            }
+        });
+
+        waits(0);
+
+        runs(function() {
+            page.evaluate(function() { 
+                console.log("PASS");
+            });
+            page.evaluate(testPrimitiveArgs, 
+                true,
+                0,
+                "`~!@#$%^&*()_+-=[]\{}|;':\",./<>?",
+                undefined,
+                null);
+            page.evaluate(testComplexArgs,
+                {a:true, b:0, c:"string"},
+                function() { return true; },
+                [true, 0, "string"],
+                /\d+\w*\//);
+            expect(message).toEqual("PASS");
+        });
+    });
 });
 
 describe("WebPage construction with options", function () {