first sane version

.gitignore

@@ -43,3 +43,6 @@ build/
 build_wasm/
 
 bld
+
+#  macOS
+.DS_Store

CMakeLists.txt

@@ -284,6 +284,7 @@ if(EMSCRIPTEN)
         PUBLIC "SHELL: -s ASYNCIFY"
         PUBLIC "SHELL: -s FORCE_FILESYSTEM=1"
         PUBLIC "SHELL: --pre-js ${CMAKE_CURRENT_SOURCE_DIR}/src/pre.js"
+        PUBLIC "SHELL: --post-js ${CMAKE_CURRENT_SOURCE_DIR}/src/post.js"
     )
 endif()
 

notebooks/xeus-javascript.ipynb

@@ -14,6 +14,17 @@
     "# Simple code execution"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "plaintext"
+    }
+   },
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -108,8 +119,7 @@
    "metadata": {},
    "source": [
     "# Scope\n",
-    "all variables declared via `const` or `let` are scoped to the cell they are declared in and are not accessible from other cells.\n",
-    "All variables declared via `var` are scoped to the notebook and are accessible from other cells."
+    "all toplevel variables (const/let/var) are accessible from other cells."
    ]
   },
   {
@@ -126,6 +136,17 @@
     "let fubar_local=43;"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "plaintext"
+    }
+   },
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -150,9 +171,47 @@
    },
    "outputs": [],
    "source": [
-    "// this does not\n",
+    "// this also works\n",
+    "\n",
     "console.log(fubar_local)"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Const reassignment\n",
+    "within a cell, const cannot be reassigned, but it can be reassigned in another cell, or\n",
+    "when the cell is re-executed."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "plaintext"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "const some_const_var = 42;\n",
+    "pp(some_const_var)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "plaintext"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "const some_const_var = 43;\n",
+    "pp(some_const_var)"
+   ]
   }
  ],
  "metadata": {

src/post.js

@@ -0,0 +1,2 @@
+
+Module["FS"] = FS;

src/pre.js

@@ -1,40 +1,67 @@
 Module["_make_async_from_code"] = function (code) {
 
-    let async_function = Function(`
-        const afunc = async function(){
+    const code_ast = Module["_ast_parse"](code);
+    let extra_code = [];
+    for(const node of code_ast.body){
+        if(node.type == "FunctionDeclaration")
+        {
+            const  name = node.id.name;
+            extra_code.push(`globalThis[\'${name}\'] = eval(${name})`);
+        }
+        else if(node.type == "VariableDeclaration")
+        {
+            const  name = node.declarations[0].id.name;
+            extra_code.push(`globalThis[\'${name}\'] = eval(${name})`);
+        }
+    }
+    const ec = extra_code.join('\n');
+    const total_code =  code.concat('\n', ec);
 
-            function __storeVars(target) {
-                return new Proxy(target, {
-                  has(target, prop) { return true; },
-                  get(target, prop) {
-                    if(prop in target){
-                        return target[prop];
-                    }
-                    else{
-                        if (typeof globalThis[prop] === 'function') {
-                            return globalThis[prop].bind(globalThis);
-                        }
-                        return globalThis[prop];
-                    }
-                 }
-                });
-            }
-            let __stored_vars = {};
 
-            with(__storeVars(__stored_vars)) {
-                ${code}
-            }
-            for (const [key, value] of Object.entries(__stored_vars)) {
-                globalThis[key] = value
-            }
+    let async_function = Function(`
+        const afunc = async function(){
+            ${total_code}
         }
         return afunc;
     `)();
     return async_function;
 }
 
+Module["_ast_parse_options"] = {
+    ranges: true
+};
+
+Module["_ast_parse"] = function (code) {
+    return globalThis["meriyah"].parseScript(code, Module["_ast_parse_options"]);
+}
+
 Module["_configure"] = function () {
-    _clog = console.log;
+
+    console.log("import meriyah");
+    const url="https://cdn.jsdelivr.net/npm/meriyah@4.3.9/dist/meriyah.umd.min.js"
+    importScripts(url);
+
+
+
+    globalThis.ijs
+    globalThis.pprint = function(...args){
+        // stringify all with 2 spaces
+        // and join with space
+        // and add newline at the end
+
+        let msg = ""
+        for (let i = 0; i < args.length; i++) {
+            msg += `${JSON.stringify(args[i], null, 2)}`;
+            if (i < args.length - 1) {
+                msg += " ";
+            }
+        }
+        Module["_publish_stdout_stream"](`${msg}\n`);
+    }
+    // alias
+    globalThis.pp = globalThis.pprint;
+
+
     console.log = function (... args) {
         let msg = ""
         for (let i = 0; i < args.length; i++) {
@@ -45,7 +72,6 @@ Module["_configure"] = function () {
         }
         Module["_publish_stdout_stream"](`${msg}\n`);
     }
-    _cerr = console.error;
     console.error = function (... args) {
         let msg = ""
         for (let i = 0; i < args.length; i++) {
@@ -62,6 +88,7 @@ Module["_configure"] = function () {
 }
 
 Module["_call_user_code"] =  async function (code) {
+
     try{
         const async_function =  Module["_make_async_from_code"](code);
         await async_function();
@@ -70,13 +97,39 @@ Module["_call_user_code"] =  async function (code) {
         }
     }
     catch(err){
+
+        // if the error is an integer,  then
+        // its a c++ exception ptr
+        // so we need to get the error message
+
+        if(typeof err === "number"){
+            console.log("catched c++ exception", err);
+            let msg = Module["get_exception_message"](err);
+
+            // if promise
+            if(msg instanceof Promise){
+                console.log("awaiting promise");
+                msg = await msg;
+            }
+
+
+            console.log("msg", msg);
+            return{
+                error_type: "C++ Exception",
+                error_message: `${msg}`,
+                error_stack: "",
+                has_error: true
+            }
+        }
+
         return{
             error_type: `${err.name || "UnkwownError"}`,
             error_message: `${err.message || ""}`,
             error_stack: `${err.stack || ""}`,
             has_error: true
         }
     }
+
 }
 
 

src/xinterpreter.cpp

@@ -19,6 +19,7 @@
 
 // embind
 #include <emscripten/bind.h>
+#include <emscripten/emscripten.h>
 
 #include <sstream>
 
@@ -51,6 +52,7 @@ namespace xeus_javascript
 
         // std::cout<<"display_data"<<std::endl;
 
+
         // publish stream
         interpreter.display_data(
             data["data"],
@@ -62,7 +64,7 @@ namespace xeus_javascript
 
     interpreter::interpreter()
     {
-        std::cout<<"V44"<<std::endl;
+        std::cout<<"Welcome to the 60th iteration of this file kernel (due to the service worker caching I need to print this to keep sanity)"<<std::endl;
         xeus::register_interpreter(this);
     }
 
@@ -75,6 +77,8 @@ namespace xeus_javascript
     {
         nl::json kernel_res;
 
+
+
         auto result_promise = emscripten::val::module_property("_call_user_code")(code);
         auto result = result_promise.await();
         if(result["has_error"].as<bool>()) {
@@ -100,7 +104,8 @@ namespace xeus_javascript
         }
 
 
-       return xeus::create_successful_reply(nl::json::array(), nl::json::object());
+
+        return xeus::create_successful_reply(nl::json::array(), nl::json::object());
     }
 
     void interpreter::configure_impl()