following tutorial

Cargo.toml

@@ -7,6 +7,12 @@ edition = "2018"
 [lib]
 crate-type = ["cdylib", "rlib"]
 
+[dependencies.web-sys]
+version = "0.3"
+features = [
+    "console",
+]
+
 [features]
 default = ["console_error_panic_hook"]
 

src/lib.rs

@@ -3,6 +3,15 @@ mod utils;
 use std::fmt;
 use wasm_bindgen::prelude::*;
 
+extern crate web_sys;
+
+// A macro to provide `println!(..)`-style syntax for `console.log` logging.
+macro_rules! log {
+    ( $( $t:tt )* ) => {
+        web_sys::console::log_1(&format!( $( $t )* ).into());
+    }
+}
+
 // When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
 // allocator.
 #[cfg(feature = "wee_alloc")]
@@ -63,6 +72,14 @@ impl Universe {
                 let cell = self.cells[idx];
                 let live_neighbors = self.live_neighbor_count(row, col);
 
+                log!(
+                    "cell[{}, {}] is initially {:?} and has {} live neighbors",
+                    row,
+                    col,
+                    cell,
+                    live_neighbors
+                );
+
                 let next_cell = match (cell, live_neighbors) {
                     // Rule 1: Any live cell with fewer than two live neighbours
                     // dies, as if caused by underpopulation.
@@ -88,6 +105,8 @@ impl Universe {
     }
 
     pub fn new() -> Universe {
+        utils::set_panic_hook();
+
         let width = 64;
         let height = 64;
 

www/index.js

@@ -21,6 +21,7 @@ canvas.width = (CELL_SIZE + 1) * width + 1;
 const ctx = canvas.getContext('2d');
 
 const renderLoop = () => {
+    debugger;
     universe.tick();
 
     drawGrid();