res: add .is()

docs/api/request.md

@@ -167,7 +167,7 @@ this.body = yield db.find('something');
  If `app.subdomainOffset` is not set, this.subdomains is `["ferrets", "tobi"]`.
  If `app.subdomainOffset` is 3, this.subdomains is `["tobi"]`.
 
-### req.is(type)
+### req.is(types...)
 
  Check if the incoming request contains the "Content-Type"
  header field, and it contains any of the give mime `type`s.
@@ -346,4 +346,3 @@ this.acceptsLanguages();
 ### req.get(field)
 
  Return request header.
-

docs/api/response.md

@@ -20,7 +20,7 @@
 
 ### res.status=
 
- Set response status via numeric code or case-insensitive string:
+ Set response status via numeric code:
 
  - 100 "continue"
  - 101 "switching protocols"
@@ -182,6 +182,33 @@ this.type = 'png';
  when explicitly defined in full as `res.type = 'text/html'`
  no charset is assigned.
 
+### res.is(types...)
+
+ Very similar to `this.request.is()`.
+ Check whether the response type is one of the supplied types.
+ This is particularly useful for creating middleware that
+ change certain responses.
+
+ For example, this is a middleware that minifies
+ all HTML response except for streamss.
+
+```js
+var minify = require('html-minifier');
+
+app.use(function *minifyHTML(next){
+ yield* next;
+
+ if (!this.response.is('html')) return;
+
+ var body = this.response.body;
+ if (!body) return;
+ // too difficult to do this with a stream
+ if ('function' == typeof body.pipe) return;
+ if (Buffer.isBuffer(body)) body = body.toString('utf8');
+ this.response.body = minify(body);
+});
+```
+
 ### res.redirect(url, [alt])
 
  Perform a [302] redirect to `url`.

lib/response.js

@@ -8,6 +8,7 @@ var getType = require('mime-types').contentType;
 var isJSON = require('koa-is-json');
 var escape = require('escape-html');
 var onfinish = require('finished');
+var typeis = require('type-is').is;
 var status = require('statuses');
 var destroy = require('dethroy');
 var assert = require('assert');
@@ -338,6 +339,22 @@ module.exports = {
  return type.split(';')[0];
  },
 
+ /**
+ * Check whether the response is one of the listed types.
+ * Pretty much the same as `this.request.is()`.
+ *
+ * @param {String|Array} types...
+ * @return {String|false}
+ * @api public
+ */
+
+ is: function(types){
+ var type = this.type;
+ if (!types) return type || false;
+ if (!Array.isArray(types)) types = [].slice.call(arguments);
+ return typeis(type, types);
+ },
+
  /**
  * Return response header.
  *

test/response/is.js

@@ -0,0 +1,80 @@
+
+var context = require('../context');
+var should = require('should');
+var assert = require('assert');
+
+describe('response.is(type)', function(){
+ it('should ignore params', function(){
+ var res = context().response;
+ res.type = 'text/html; charset=utf-8';
+
+ res.is('text/*').should.equal('text/html');
+ })
+
+ describe('when no type is set', function(){
+ it('should return false', function(){
+ var res = context().response;
+
+ assert(false === res.is());
+ assert(false === res.is('html'));
+ })
+ })
+
+ describe('when given no types', function(){
+ it('should return the type', function(){
+ var res = context().response;
+ res.type = 'text/html; charset=utf-8';
+
+ res.is().should.equal('text/html');
+ })
+ })
+
+ describe('given one type', function(){
+ it('should return the type or false', function(){
+ var res = context().response;
+ res.type = 'image/png';
+
+ res.is('png').should.equal('png');
+ res.is('.png').should.equal('.png');
+ res.is('image/png').should.equal('image/png');
+ res.is('image/*').should.equal('image/png');
+ res.is('*/png').should.equal('image/png');
+
+ res.is('jpeg').should.be.false;
+ res.is('.jpeg').should.be.false;
+ res.is('image/jpeg').should.be.false;
+ res.is('text/*').should.be.false;
+ res.is('*/jpeg').should.be.false;
+ })
+ })
+
+ describe('given multiple types', function(){
+ it('should return the first match or false', function(){
+ var res = context().response;
+ res.type = 'image/png';
+
+ res.is('png').should.equal('png');
+ res.is('.png').should.equal('.png');
+ res.is('text/*', 'image/*').should.equal('image/png');
+ res.is('image/*', 'text/*').should.equal('image/png');
+ res.is('image/*', 'image/png').should.equal('image/png');
+ res.is('image/png', 'image/*').should.equal('image/png');
+
+ res.is('jpeg').should.be.false;
+ res.is('.jpeg').should.be.false;
+ res.is('text/*', 'application/*').should.be.false;
+ res.is('text/html', 'text/plain', 'application/json; charset=utf-8').should.be.false;
+ })
+ })
+
+ describe('when Content-Type: application/x-www-form-urlencoded', function(){
+ it('should match "urlencoded"', function(){
+ var res = context().response;
+ res.type = 'application/x-www-form-urlencoded';
+
+ res.is('urlencoded').should.equal('urlencoded');
+ res.is('json', 'urlencoded').should.equal('urlencoded');
+ res.is('urlencoded', 'json').should.equal('urlencoded');
+ })
+ })
+})