Package description
The etag npm package is used to generate HTTP ETags, which are typically used for cache validation. It can generate ETags based on the contents of a file or a buffer, a string, or based on a specified entity and its attributes.
Generating ETags from a file
This code sample demonstrates how to generate an ETag for the contents of a file. It reads the file 'example.txt' and uses the etag function to create an ETag based on the file's contents.
const etag = require('etag');
const fs = require('fs');
fs.readFile('example.txt', function(err, data) {
if (err) throw err;
const eTagValue = etag(data);
console.log(eTagValue);
});Generating ETags from a string
This code sample shows how to generate an ETag from a string. The etag function is called with a string 'Hello, World!' to produce an ETag for that specific string.
const etag = require('etag');
const entity = 'Hello, World!';
const eTagValue = etag(entity);
console.log(eTagValue);Generating ETags with options
This example illustrates how to generate a weak ETag by passing an options object to the etag function. The options object specifies that the ETag should be weak, which is indicated by a 'W/' prefix in the ETag value.
const etag = require('etag');
const entity = Buffer.from('Hello, World!');
const options = { weak: true };
const eTagValue = etag(entity, options);
console.log(eTagValue);The 'fresh' package is used to check if the HTTP response is still 'fresh' on the client side. It is similar to etag in that it deals with HTTP caching mechanisms, but it focuses on cache validation rather than ETag generation.
The 'cacheable-response' package is a higher-level abstraction for creating cacheable responses in Node.js servers. It uses ETags among other headers to manage caching. It provides a more comprehensive solution compared to etag, which is focused solely on ETag generation.
Readme
Create simple ETags
$ npm install etag
var etag = require('etag')
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))
etag accepts these properties in the options object.
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.
$ npm test
$ npm run-script bench
> etag@1.6.0 bench nodejs-etag
> node benchmark/index.js
http_parser@1.0
node@0.10.33
v8@3.14.5.9
ares@1.9.0-DEV
uv@0.10.29
zlib@1.2.3
modules@11
openssl@1.0.1j
> node benchmark/body0-100b.js
100B body
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* buffer - strong x 289,198 ops/sec ±1.09% (190 runs sampled)
* buffer - weak x 287,838 ops/sec ±0.91% (189 runs sampled)
* string - strong x 284,586 ops/sec ±1.05% (192 runs sampled)
* string - weak x 287,439 ops/sec ±0.82% (192 runs sampled)
> node benchmark/body1-1kb.js
1KB body
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* buffer - strong x 212,423 ops/sec ±0.75% (193 runs sampled)
* buffer - weak x 211,871 ops/sec ±0.74% (194 runs sampled)
string - strong x 205,291 ops/sec ±0.86% (194 runs sampled)
string - weak x 208,463 ops/sec ±0.79% (192 runs sampled)
> node benchmark/body2-5kb.js
5KB body
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* buffer - strong x 92,901 ops/sec ±0.58% (195 runs sampled)
* buffer - weak x 93,045 ops/sec ±0.65% (192 runs sampled)
string - strong x 89,621 ops/sec ±0.68% (194 runs sampled)
string - weak x 90,070 ops/sec ±0.70% (196 runs sampled)
> node benchmark/body3-10kb.js
10KB body
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* buffer - strong x 54,220 ops/sec ±0.85% (192 runs sampled)
* buffer - weak x 54,069 ops/sec ±0.83% (191 runs sampled)
string - strong x 53,078 ops/sec ±0.53% (194 runs sampled)
string - weak x 53,849 ops/sec ±0.47% (197 runs sampled)
> node benchmark/body4-100kb.js
100KB body
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* buffer - strong x 6,673 ops/sec ±0.15% (197 runs sampled)
* buffer - weak x 6,716 ops/sec ±0.12% (198 runs sampled)
string - strong x 6,357 ops/sec ±0.14% (197 runs sampled)
string - weak x 6,344 ops/sec ±0.21% (197 runs sampled)
> node benchmark/stats.js
stats
1 test completed.
2 tests completed.
3 tests completed.
4 tests completed.
* real - strong x 1,671,989 ops/sec ±0.13% (197 runs sampled)
* real - weak x 1,681,297 ops/sec ±0.12% (198 runs sampled)
fake - strong x 927,063 ops/sec ±0.14% (198 runs sampled)
fake - weak x 914,461 ops/sec ±0.41% (191 runs sampled)
FAQs
Create simple HTTP ETags
We found that etag demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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