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Infer the content-type of a request.

This is aNode.js module available through thenpm registry. Installation is done using thenpm install command:

$ npm install type-is

varhttp=require('http')vartypeis=require('type-is')http.createServer(function(req,res){varistext=typeis(req,['text/*'])res.end('you '+(istext ?'sent' :'did not send')+' me text')})

Checks if therequest is one of thetypes. If the request has no body,even if there is aContent-Type header, thennull is returned. If theContent-Type header is invalid or does not matches any of thetypes, thenfalse is returned. Otherwise, a string of the type that matched is returned.

Therequest argument is expected to be a Node.js HTTP request. Thetypesargument is an array of type strings.

Each type in thetypes array can be one of the following:

• A file extension name such asjson. This name will be returned if matched.
• A mime type such asapplication/json.
• A mime type with a wildcard such as*/* or*/json orapplication/*.The full mime type will be returned if matched.
• A suffix such as+json. This can be combined with a wildcard such as*/vnd+json orapplication/*+json. The full mime type will be returnedif matched.

Some examples to illustrate the inputs and returned value:

// req.headers.content-type = 'application/json'typeis(req,['json'])// => 'json'typeis(req,['html','json'])// => 'json'typeis(req,['application/*'])// => 'application/json'typeis(req,['application/json'])// => 'application/json'typeis(req,['html'])// => false

Returns a Boolean if the givenrequest has a body, regardless of theContent-Type header.

Having a body has no relation to how large the body is (it may be 0 bytes).This is similar to how file existence works. If a body does exist, then thisindicates that there is data to read from the Node.js request stream.

if(typeis.hasBody(req)){// read the body, since there is onereq.on('data',function(chunk){// ...})}

Checks if themediaType is one of thetypes. If themediaType is invalidor does not matches any of thetypes, thenfalse is returned. Otherwise, astring of the type that matched is returned.

ThemediaType argument is expected to be amedia type string. Thetypes argumentis an array of type strings.

Each type in thetypes array can be one of the following:

• A file extension name such asjson. This name will be returned if matched.
• A mime type such asapplication/json.
• A mime type with a wildcard such as*/* or*/json orapplication/*.The full mime type will be returned if matched.
• A suffix such as+json. This can be combined with a wildcard such as*/vnd+json orapplication/*+json. The full mime type will be returnedif matched.

Some examples to illustrate the inputs and returned value:

varmediaType='application/json'typeis.is(mediaType,['json'])// => 'json'typeis.is(mediaType,['html','json'])// => 'json'typeis.is(mediaType,['application/*'])// => 'application/json'typeis.is(mediaType,['application/json'])// => 'application/json'typeis.is(mediaType,['html'])// => false

Match the type stringexpected withactual, taking in to account wildcards.A wildcard can only be in the type of the subtype part of a media type and onlyin theexpected value (asactual should be the real media type to match). Asuffix can still be included even with a wildcard subtype. If an input ismalformed,false will be returned.

typeis.match('text/html','text/html')// => truetypeis.match('*/html','text/html')// => truetypeis.match('text/*','text/html')// => truetypeis.match('*/*','text/html')// => truetypeis.match('*/*+json','application/x-custom+json')// => true

Normalize atype string. This works by performing the following:

• If thetype is not a string,false is returned.
• If the string starts with+ (so it is a+suffix shorthand like+json),then it is expanded to contain the complete wildcard notation of*/*+suffix.
• If the string contains a/, then it is returned as the type.
• Else the string is assumed to be a file extension and the mapped media type isreturned, orfalse is there is no mapping.

This includes two special mappings:

• 'multipart' ->'multipart/*'
• 'urlencoded' ->'application/x-www-form-urlencoded'

varexpress=require('express')vartypeis=require('type-is')varapp=express()app.use(functionbodyParser(req,res,next){if(!typeis.hasBody(req)){returnnext()}switch(typeis(req,['urlencoded','json','multipart'])){case'urlencoded':// parse urlencoded bodythrownewError('implement urlencoded body parsing')case'json':// parse json bodythrownewError('implement json body parsing')case'multipart':// parse multipart bodythrownewError('implement multipart body parsing')default:// 415 error coderes.statusCode=415res.end()break}})

MIT