A blazing fast, memory efficient ECMAScript parser written in C and compiled to WebAssembly. It is a standalone library with no dependencies and a lean code. The library can be compiled to WebAssembly without the need for heavy toolchains such as Emscripten. Hence the glue code required to load the WebAssembly code is minimal.
On average falcon parser is 5x-7x faster than the best performing cold run library web-tree-sitter, while 3x-4x faster than the best performing hot run library meriyah.
Benchmark results of cold parse times computed with benchmark.js library are tabulated below. Each parse is executed in a separate worker thread to prevent JIT compiler optimizations from kicking in.
| falcon-0.x.0 | acorn-8.0.1 | meriyah-2.1.0 | tree-sitter-0.17.1 | |
|---|---|---|---|---|
| jquery-3.5.1.js | 6.9 ms ± 3% |
127.6 ms ± 1% |
83.1 ms ± 1% |
45.0 ms ± 2% |
| angular-1.8.0.js | 22.0 ms ± 2% |
217.3 ms ± 1% |
176.0 ms ± 1% |
108.8 ms ± 3% |
| react-17.0.1.js | 2.6 ms ± 3% |
64.9 ms ± 1% |
51.4 ms ± 3% |
18.4 ms ± 4% |
Tabulated below are the benchmark results of hot parse times which reflect JIT compiler optimizations that kick in after repetitive invocations of parsing possibly within a short span of time.
| falcon-0.x.0 | acorn-8.0.1 | meriyah-2.1.0 | tree-sitter-0.17.1 | |
|---|---|---|---|---|
| jquery-3.5.1.js | 4.6 ms ± 1% |
24.4 ms ± 8% |
16.6 ms ±18% |
38.8 ms ± 1% |
| angular-1.8.0.js | 10.0 ms ± 1% |
53.5 ms ± 8% |
45.7 ms ±13% |
99.1 ms ± 1% |
| react-17.0.1.js | 1.3 ms ± 1% |
3.9 ms ± 1% |
2.2 ms ± 2% |
12.0 ms ± 1% |
The above benchmarks measure pure parsing performance. Accessing syntax tree built on the WebAssembly side via JavaScript bindings introduces additional overheads. WebAssembly GC Propsoal will reduce these overheads.