assets/js/bitstring.mjs (1)

259-259: Allocating lookup-table objects per call in hot-path methods.

Both decodeUtf8CodePoint (line 259) and isValidUtf8CodePoint (line 630) recreate a small object literal on every invocation. These are called in the O(n) scan inside getValidUtf8Length, once per multi-byte sequence.

The firstByteMasks values follow the pattern 0x7f >> length, which avoids the allocation entirely, and minValueForLength can be a module-level constant array.

♻️ Zero-allocation alternatives

  static decodeUtf8CodePoint(bytes, start, length) {
    if (length === 1) return bytes[start];

-   // First byte masks: 2-byte=0x1f, 3-byte=0x0f, 4-byte=0x07
-   const firstByteMasks = {2: 0x1f, 3: 0x0f, 4: 0x07};
-
-   let codePoint = bytes[start] & firstByteMasks[length];
+   // First byte masks: 2→0x1f, 3→0x0f, 4→0x07 (formula: 0x7f >> length)
+   let codePoint = bytes[start] & (0x7f >> length);

    for (let i = 1; i < length; i++) {

For isValidUtf8CodePoint, hoist minValueForLength to a module-level (or class-level) constant:

+// Module-level constant; indices 0–4, only 1–4 used.
+const UTF8_MIN_CODE_POINT = [0, 0, 0x80, 0x800, 0x10000];

  static isValidUtf8CodePoint(codePoint, encodingLength) {
-   const minValueForLength = {1: 0, 2: 0x80, 3: 0x800, 4: 0x10000};
-   if (codePoint < minValueForLength[encodingLength]) return false;
+   if (codePoint < UTF8_MIN_CODE_POINT[encodingLength]) return false;

Also applies to: 630-630

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@assets/js/bitstring.mjs` at line 259, The code repeatedly allocates small
lookup objects inside hot-path functions decodeUtf8CodePoint and
isValidUtf8CodePoint (e.g. firstByteMasks and minValueForLength); hoist these to
module-level constants and replace the firstByteMasks literal with the computed
pattern (use 0x7f >> length) or a precomputed array to avoid per-call object
creation, and make minValueForLength a shared constant array used by both
functions.