rework assert, wasm_alert, wasm_clear, expect

package/index.html

@@ -104,6 +104,9 @@ const mem = new memory_t(new WebAssembly['Memory']({ initial: 2000, maximum: 655
             ctx2d.fillStyle = `rgba(${r}, ${g}, ${b}, ${a})`;
             ctx2d.fill();
         },
+        wasm_clear: () => {
+            ctx2d.clearRect(0, 0, canvas.width, canvas.height);
+        },
         wasm_set_clip: (x, y, w, h) => {
             ctx2d.restore();
             ctx2d.save();
@@ -115,6 +118,11 @@ const mem = new memory_t(new WebAssembly['Memory']({ initial: 2000, maximum: 655
             return parseFloat(mem.read_cstr(str, len));
         },
         wasm_trap: () => { throw new Error() },
+        wasm_alert: (str, len) => {
+            const string = mem.read_cstr(str,len);
+            console.log(string);
+            alert(string);
+        },
     };
 
     const program = await WebAssembly['instantiate'](binary, { "env": wasm_imports });