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, `Buffer`s, 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@1.8.1 bench nodejs-etag
> node benchmark/index.js
http_parser@2.7.0
node@6.11.1
v8@5.1.281.103
uv@1.11.0
zlib@1.2.11
ares@1.10.1-DEV
icu@58.2
modules@48
openssl@1.0.2k
> node benchmark/body0-100b.js
100B body
4 tests completed.
buffer - strong x 258,647 ops/sec ±1.07% (180 runs sampled)
buffer - weak x 263,812 ops/sec ±0.61% (184 runs sampled)
string - strong x 259,955 ops/sec ±1.19% (185 runs sampled)
string - weak x 264,356 ops/sec ±1.09% (184 runs sampled)
> node benchmark/body1-1kb.js
1KB body
4 tests completed.
buffer - strong x 189,018 ops/sec ±1.12% (182 runs sampled)
buffer - weak x 190,586 ops/sec ±0.81% (186 runs sampled)
string - strong x 144,272 ops/sec ±0.96% (188 runs sampled)
string - weak x 145,380 ops/sec ±1.43% (187 runs sampled)
> node benchmark/body2-5kb.js
5KB body
4 tests completed.
buffer - strong x 92,435 ops/sec ±0.42% (188 runs sampled)
buffer - weak x 92,373 ops/sec ±0.58% (189 runs sampled)
string - strong x 48,850 ops/sec ±0.56% (186 runs sampled)
string - weak x 49,380 ops/sec ±0.56% (190 runs sampled)
> node benchmark/body3-10kb.js
10KB body
4 tests completed.
buffer - strong x 55,989 ops/sec ±0.93% (188 runs sampled)
buffer - weak x 56,148 ops/sec ±0.55% (190 runs sampled)
string - strong x 27,345 ops/sec ±0.43% (188 runs sampled)
string - weak x 27,496 ops/sec ±0.45% (190 runs sampled)
> node benchmark/body4-100kb.js
100KB body
4 tests completed.
buffer - strong x 7,083 ops/sec ±0.22% (190 runs sampled)
buffer - weak x 7,115 ops/sec ±0.26% (191 runs sampled)
string - strong x 3,068 ops/sec ±0.34% (190 runs sampled)
string - weak x 3,096 ops/sec ±0.35% (190 runs sampled)
> node benchmark/stats.js
stat
4 tests completed.
real - strong x 871,642 ops/sec ±0.34% (189 runs sampled)
real - weak x 867,613 ops/sec ±0.39% (190 runs sampled)
fake - strong x 401,051 ops/sec ±0.40% (189 runs sampled)
fake - weak x 400,100 ops/sec ±0.47% (188 runs sampled)

# License

[MIT](LICENSE)