etag

Create simple HTTP ETags

This module generates HTTP ETags (as defined in RFC 7232) for use in HTTP responses.

Installation

This is a Node.js module available through the npm registry. Installation is done using the npm install command:

$ npm install etag

API

var etag = require('etag')

etag(entity, [options])

Generate a strong ETag for the given entity. This should be the complete body of the entity. Strings, Buffers, and fs.Stats are accepted. By default, a strong ETag is generated except for fs.Stats, which will generate a weak ETag (this can be overwritten by options.weak).

res.setHeader('ETag', etag(body))

Options

etag accepts these properties in the options object.

weak

Specifies if the generated ETag will include the weak validator mark (that is, the leading W/). The actual entity tag is the same. The default value is false, unless the entity is fs.Stats, in which case it is true.

Testing

$ npm test

Benchmark

$ npm run-script bench

> etag@1.8.0 bench nodejs-etag
> node benchmark/index.js

  http_parser@2.7.0
  node@6.9.1
  v8@5.1.281.84
  uv@1.9.1
  zlib@1.2.8
  ares@1.10.1-DEV
  icu@57.1
  modules@48
  openssl@1.0.2j

> node benchmark/body0-100b.js

  100B body

  4 tests completed.

* buffer - strong x 498,600 ops/sec ±0.82% (191 runs sampled)
* buffer - weak   x 496,249 ops/sec ±0.59% (179 runs sampled)
  string - strong x 466,298 ops/sec ±0.88% (186 runs sampled)
  string - weak   x 464,298 ops/sec ±0.84% (184 runs sampled)

> node benchmark/body1-1kb.js

  1KB body

  4 tests completed.

* buffer - strong x 346,535 ops/sec ±0.32% (189 runs sampled)
* buffer - weak   x 344,958 ops/sec ±0.52% (185 runs sampled)
  string - strong x 259,672 ops/sec ±0.82% (191 runs sampled)
  string - weak   x 260,931 ops/sec ±0.76% (190 runs sampled)

> node benchmark/body2-5kb.js

  5KB body

  4 tests completed.

* buffer - strong x 136,510 ops/sec ±0.62% (189 runs sampled)
* buffer - weak   x 136,604 ops/sec ±0.51% (191 runs sampled)
  string - strong x  80,903 ops/sec ±0.84% (192 runs sampled)
  string - weak   x  82,785 ops/sec ±0.50% (193 runs sampled)

> node benchmark/body3-10kb.js

  10KB body

  4 tests completed.

* buffer - strong x 78,650 ops/sec ±0.31% (193 runs sampled)
* buffer - weak   x 78,685 ops/sec ±0.41% (193 runs sampled)
  string - strong x 43,999 ops/sec ±0.43% (193 runs sampled)
  string - weak   x 44,081 ops/sec ±0.45% (192 runs sampled)

> node benchmark/body4-100kb.js

  100KB body

  4 tests completed.

  buffer - strong x 8,860 ops/sec ±0.66% (191 runs sampled)
* buffer - weak   x 9,030 ops/sec ±0.26% (193 runs sampled)
  string - strong x 4,838 ops/sec ±0.16% (194 runs sampled)
  string - weak   x 4,800 ops/sec ±0.52% (192 runs sampled)

> node benchmark/stats.js

  stat

  4 tests completed.

* real - strong x 1,468,073 ops/sec ±0.32% (191 runs sampled)
* real - weak   x 1,446,852 ops/sec ±0.64% (190 runs sampled)
  fake - strong x   635,707 ops/sec ±0.33% (194 runs sampled)
  fake - weak   x   627,708 ops/sec ±0.36% (192 runs sampled)

License

MIT