Support more bit array options for ints and floats on JavaScript

CHANGELOG.md

@@ -80,7 +80,7 @@
   Unsupported feature for Javascript since they would already cause
   a runtime error on Javascript.
 
-  This means if you compile specifically for Javascript you will now recieve
+  This means if you compile specifically for Javascript you will now receive
   this error:
 
   ```
@@ -132,6 +132,11 @@
 - When compiling to JavaScript constants will now be annotated as `@__PURE__`.
   ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
 
+- The `little` and `big` endianness options, the `signed` and `unsigned` integer
+  options, and sized floats (32-bit and 64-bit), can now be used in bit array
+  expressions and patterns on the JavaScript target.
+  ([Richard Viney](https://github.com/richard-viney))
+
 ### Formatter
 
 ### Language Server

compiler-core/src/bit_array.rs

@@ -178,7 +178,7 @@ where
         }
     }
 
-    // Endianness is only valid for int, utf6, utf32 and float
+    // Endianness is only valid for int, utf16, utf32 and float
     match categories {
         SegmentOptionCategories {
             typ: None | Some(Int { .. } | Utf16 { .. } | Utf32 { .. } | Float { .. }),

compiler-core/src/javascript.rs

@@ -1,3 +1,4 @@
+mod endianness;
 mod expression;
 mod import;
 mod pattern;
@@ -167,7 +168,7 @@ impl<'a> Generator<'a> {
         };
 
         if self.tracker.float_bit_array_segment_used {
-            self.register_prelude_usage(&mut imports, "float64Bits", None);
+            self.register_prelude_usage(&mut imports, "sizedFloat", None);
         };
 
         // Put it all together

compiler-core/src/javascript/endianness.rs

@@ -0,0 +1,11 @@
+#[derive(Debug, PartialEq)]
+pub enum Endianness {
+    Big,
+    Little,
+}
+
+impl Endianness {
+    pub fn is_big(&self) -> bool {
+        *self == Endianness::Big
+    }
+}