nginx-etag

generate an etag like nginx

var etag = require('nginx-etag')

var tag = etag(Date.now()/1000,10)

console.log(tag)

will print something like '"57755bb3-a"'

api

tag = etag(modified timestamp in seconds, length on content)

object = etag.parse(tag)

• object.mtime
• object.length

etag.fromFile(filePath,callback)

• filePath is the path the the file you want to generate a tag for
• callback(err,tag)

content based api

tag = etag.contentBased(content)

rather than using the modified time value directly, this uses the first 32 bit int from the md5 hash of the content to use as the basis for the etag

object = etag.parseContentBased(tag)

• object.checksum
• object.length

etag.setContentBased(filePath,callback)

this sets the file's modified timestamp to the md5 number of it's data. because nginx uses the mtime this allows you to make etags that can be distributed accross hosts with only the data itself.

• filePath is the path the the file that you want toupdate the mtime for.
• callback(err)

to read the etag correctly be sure to pass to etag.parseContentBased

example.

etag.fromFile(filePath,function(err,tag){
  var obj = etag.parseContentBased(tag)
  console.log(obj)
})