diff --git a/src/lib.rs b/src/lib.rs
index f1b9676..5503e67 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,6 +10,14 @@ static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
 
 pub type DrawResult<T> = Result<T, Box<dyn std::error::Error>>;
 
+#[wasm_bindgen]
+extern "C" {
+    // Use `js_namespace` here to bind `console.log(..)` instead of just
+    // `log(..)`
+    #[wasm_bindgen(js_namespace = console)]
+    fn log(s: &str);
+}
+
 /// Result of screen to chart coordinates conversion.
 #[wasm_bindgen]
 pub struct Point {
@@ -62,6 +70,7 @@ impl ChartManager {
     pub fn init_panic_hook() { panic::set_hook(Box::new(console_error_panic_hook::hook)); }
 
     fn get_back_cache(&self) -> Vec<(f32, f32)> {
+        log("Using back_cache");
         match &self.back_cache {
             Some(x) => x.clone(),
             None => panic!("use_back_cache is true, but back_cache is None!"),
@@ -69,6 +78,7 @@ impl ChartManager {
     }
 
     fn get_front_cache(&self) -> (Vec<(f32, f32, f32)>, f32) {
+        log("Using front_cache");
         match &self.front_cache {
             Some(x) => x.clone(),
             None => panic!("use_front_cache is true, but front_cache is None!"),
@@ -82,7 +92,6 @@ impl ChartManager {
         let func = expr.bind("x").unwrap();
 
         let backend = CanvasBackend::with_canvas_object(element).unwrap();
-
         let root = backend.into_drawing_area();
         let font: FontDesc = ("sans-serif", 20.0).into();
 
@@ -101,6 +110,7 @@ impl ChartManager {
         let data: Vec<(f32, f32)> = match self.use_back_cache {
             true => self.get_back_cache(),
             false => {
+                log("Updating back_cache");
                 let output: Vec<(f32, f32)> = (1..=self.resolution)
                     .map(|x| ((x as f32 / self.resolution as f32) * absrange) + self.min_x)
                     .map(|x| (x, func(x as f64) as f32))
@@ -113,9 +123,10 @@ impl ChartManager {
 
         chart.draw_series(LineSeries::new(data, &RED))?;
 
-        let (data2, area): (Vec<(f32, f32, f32)>, f32) = match self.use_front_cache {
+        let (rect_data, area): (Vec<(f32, f32, f32)>, f32) = match self.use_front_cache {
             true => self.get_front_cache(),
             false => {
+                log("Updating front_cache");
                 let step = absrange / (self.num_interval as f32);
                 let output: (Vec<(f32, f32, f32)>, f32) = self.integral_rectangles(step, &func);
                 self.front_cache = Some(output.clone());
@@ -125,7 +136,7 @@ impl ChartManager {
 
         // Draw rectangles
         chart.draw_series(
-            data2
+            rect_data
                 .iter()
                 .map(|(x1, x2, y)| Rectangle::new([(*x2, *y), (*x1, 0.0)], &BLUE)),
         )?;