One of the challenges of working with Javascript and libxml is that they use different encodings for strings. Javascript uses UTF-16/UCS-2, while libxml uses UTF-8. This means that we have to convert the strings every time we call a function from libxml.

To avoid this overhead, this library offers two types of parsing functions: String API and Buffer API. The String API takes a Javascript string as input and converts it to a UTF-8 buffer before parsing. The Buffer API takes a UTF-8 buffer as input and parses it directly. The Buffer API is faster than the String API, especially for large XML documents. Therefore, we recommend using the Buffer API whenever possible to improve the performance of your code.

Benchmark

The benchmark report below is for the performance of DOM tree parsing, among the following libraries

• Bindings of libxml
  • String API of libxml2-wasm
  • Buffer API of libxml2-wasm
  • libxmljs2
• Pure javascript implementation
  • @rgrove/parse-xml
  • fast-xml-parser
  • xmldoc

To run the benchmark, build the lib first,

npm ci && npm run build
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Then run test in benchmark directory,

cd benchmark && npm ci
npm test
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Environment: NodeJs v18.19.0 on Darwin arm64 Apple M3 Max

Running "fixtures/small.xml: 780 bytes" suite...
Progress: 100%

  libxml2-wasm:
    120 578 ops/s, ±0.12%   | 28% slower

  libxml2-wasm(buffer api):
    167 479 ops/s, ±0.37%   | fastest

  libxmljs2:
    78 688 ops/s, ±1.05%    | 53.02% slower

  @rgrove/parse-xml:
    78 790 ops/s, ±0.19%    | 52.96% slower

  fast-xml-parser:
    52 077 ops/s, ±0.27%    | 68.91% slower

  xmldoc:
    41 125 ops/s, ±0.42%    | slowest, 75.44% slower

Running "fixtures/medium.xml: 35562 bytes" suite...
Progress: 100%

  libxml2-wasm:
    6 013 ops/s, ±0.10%    | 64.87% slower

  libxml2-wasm(buffer api):
    17 114 ops/s, ±0.14%   | fastest

  libxmljs2:
    12 414 ops/s, ±1.82%   | 27.46% slower

  @rgrove/parse-xml:
    5 049 ops/s, ±0.20%    | 70.5% slower

  fast-xml-parser:
    2 708 ops/s, ±0.46%    | 84.18% slower

  xmldoc:
    1 912 ops/s, ±0.41%    | slowest, 88.83% slower

Running "fixtures/large.xml: 2337522 bytes" suite...
Progress: 100%

  libxml2-wasm:
    43 ops/s, ±0.11%   | 30.65% slower

  libxml2-wasm(buffer api):
    62 ops/s, ±0.27%   | fastest

  libxmljs2:
    50 ops/s, ±1.41%   | 19.35% slower

  @rgrove/parse-xml:
    19 ops/s, ±0.93%   | 69.35% slower

  fast-xml-parser:
    16 ops/s, ±0.37%   | 74.19% slower

  xmldoc:
    11 ops/s, ±1.13%   | slowest, 82.26% slower
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