Fix Number.prototype.toFixed()

boa_engine/Cargo.toml

@@ -63,7 +63,7 @@ num-bigint = { version = "0.4.4", features = ["serde"] }
 num-integer = "0.1.45"
 bitflags = "2.4.0"
 indexmap = "2.0.0"
-ryu-js = "0.2.2"
+ryu-js = { git = "https://github.com/boa-dev/ryu-js.git", branch = "feature/to-fixed" }
 chrono = { version = "0.4.31", default-features = false, features = ["clock", "std"] }
 fast-float = "0.2.0"
 once_cell = "1.18.0"

boa_engine/src/builtins/number/mod.rs

@@ -272,20 +272,12 @@ impl Number {
             .ok_or_else(|| {
                 JsNativeError::range()
                     .with_message("toFixed() digits argument must be between 0 and 100")
-            })? as usize;
+            })? as u8;
 
-        // 6. If x is not finite, return ! Number::toString(x).
-        if !this_num.is_finite() {
-            Ok(JsValue::new(Self::to_native_string(this_num)))
-        // 10. If x ≥ 10^21, then let m be ! ToString(𝔽(x)).
-        } else if this_num >= 1.0e21 {
-            Ok(JsValue::new(f64_to_exponential(this_num)))
-        } else {
-            // Get rid of the '-' sign for -0.0 because of 9. If x < 0, then set s to "-".
-            let this_num = if this_num == 0_f64 { 0_f64 } else { this_num };
-            let this_fixed_num = format!("{this_num:.precision$}");
-            Ok(JsValue::new(this_fixed_num))
-        }
+        let mut buffer = ryu_js::Buffer::new();
+        let string = buffer.format_to_fixed(this_num, precision);
+
+        Ok(string.into())
     }
 
     /// `Number.prototype.toLocaleString( [locales [, options]] )`

boa_engine/src/builtins/number/tests.rs

@@ -479,3 +479,12 @@ fn issue_2717() {
         TestAction::assert_eq("(0.23046743672210102).toString(36)", "0.8aoosla2phj"),
     ]);
 }
+
+// https://github.com/boa-dev/boa/issues/2609
+#[test]
+fn issue_2609() {
+    run_test_actions([
+        TestAction::assert_eq("(1.25).toFixed(1)", "1.3"),
+        TestAction::assert_eq("(1.35).toFixed(1)", "1.4"),
+    ]);
+}