Scra NPM | npm.io

scra

HTTP client, designed mainly for scraping web sites. It is not so complicated as famous request, but it is really simple tool for geting html pages for parsing data or json responses from site internal API. Sometime "less is more".

Features

GET and POST requests via HTTP/HTTPS
Supports both promise way and callback way
Proxy support via tunnel-agent
Non-utf8 charset decoding via iconv-lite
Auto decompression gzip/deflate
Easy JSON-API support
Cookies parsing/serialization
Useful request fields
Informative custom errors via c-e
No any superfluous things

Install

(node '>=10' required)

npm install scra

Usage

scra takes url string or options object as first parameter and callback function as optional second param. If no callback - scra returns promise. Any way scra produce response object, same as http.ClientRequest do, but with few extra fields.

Synopsis

const scra = require('scra');

// promise way
scra('http://httpbin.org/get')
    .then((res) => console.log(res.body))
    .catch((err) => console.error(err.message));

// callback way
scra('http://httpbin.org/get', (err, res) => {
    if(err) console.error(err.message);
    if(res) console.log(res.body);
})

See more examples in test.

Available options:

url (required) - address for request. String. If protocol is omitted in string - it will be set to http:, so example.com means http://example.com. If url is the only field in options object then first param may be this string, so scra('example.com') is equal to scra({url: 'example.com'}).
headers - http-headers for sending with a request. Object with string fields. By default there are three predefined headers:
```
{
    'connection': 'close',
    'user-agent': 'astur/scra',
    'accept': '*/*',
}
```
You may set any headers manually. Also 'Host' header will be set by node http module, and some headers may be set depending on the other options (see below). Such headers have a higher priority over values in headers option (be careful, it is not "as usual").
Manually set headers will replace defaults, but will be replaced by headers from options.
data - data for POST request. If data is a string with length more then 0 - this string will be sent as a request body without any conversions (if content-type header is not set it will be application/x-www-form-urlencoded). If data is an object it will be stringified to json and sent as a request body (content-type header will be application/json).
cookies - cookies to be sent with request. Key-value object. It will be stringified and placed to cookie header.
compressed - Boolean. If true set accept-encoding header to 'gzip, deflate'. Defaults to false.
timeout - Number of milliseconds. Time limit for request to be done (if not - error will be thrown). If timeout set to 0 it means no time limit. Defaults to 5000.
proxy - address of proxy server. It may be both, http or https, and if protocol is omitted it will be 'http'. Now scra supports proxy via tunnel-agent, so you can use proxy with https sites.
reverseProxy - object or string, describing how to change target url to reverse-proxy url. If reverseProxy is object, target url part is in field to and reverse-proxy url part is in field from. Actually it is just parameters for replace method of url string, so it is possible to use regexp in field to and replacement patterns in field from. If reverseProxy is string, scra expects it is url part before path. So, string 'http://reverse-proxy.my.org' is equal to ooject like {to: /^https?:\/\/[^/]+(\/)?/i, from: 'http://reverse-proxy.my.org$1'}
agent - custom http/https agent.

Response object extra fields:

rawBody - buffer with response body (decompressed if necessary).
charset - charset part from content-type response header.
body - response body converted to string (using iconv-lite if charset defined.) If content-type response header is application/json and body is valid json string then it will be parsed to object.
cookies - key-value object with cookies from cookies option and from set-cookie response header.
url - same as url field in options.
requestHeaders - object with headers sent with request.
requestTime - request duration (number of milliseconds).
timings - (milliseconds) detailed timings (timestamps of all request phases):
- start - time when request starts. Just moment before calling http(s).request.
- socket - time when socket has been created (when the http(s) module's socket event fires).
- lookup - time when DNS has been resolved (when the net module's lookup event fires).
- connect - time when the server acknowledges the TCP connection (when the net module's connect event fires).
- secureConnect - (https only) time when TLS handshake has been completed (when the tls module's secureConnect event fires).
- responce - time when server delivers first byte of response (when the http(s) module's responce event fires).
- end - time when all responce data has been received (when the http(s) module's end event fires).
timingPhases - (milliseconds) relative durations of each request phase:
- wait - time spent waiting for socket (timings.socket - timings.start).
- dns - time spent performing the DNS lookup (timings.lookup - timings.socket).
- tcp - time it took to establish TCP connection between a source host and destination host (timings.connect - timings.lookup).
- tls - time spent completing a TLS handshake (timings.secureConnect - timings.connect).
- responce - time spent waiting for the initial response (timings.responce - (timings.secureConnect || timings.connect)).
- read - time spent receiving the response data (timings.end - timings.responce).
- total - time spent performing all phases of request (timings.end - timings.start).
bytes - just how many bytes.sent and bytes.received by this request.
options - raw scra options parameter as string or object.

Custom errors

scra provides two custom error classes:

const scra = require('scra');
const {TimeoutError, NetworkError} = scra;

These errors contain several useful additional properties:

url - url used in current request.
errorTime - timestamp of the moment when error was thrown.
timings - same as in response field (but maybe some timings will be missing because the error occurred before corresponding phases).
timingPhases - same as in response field (but maybe some timingPhases will be missing because the error occurred before corresponding phases).
timeout - (only in TimeoutError) value of timeout option.
cause - (only in NetworkError) error object, thrown by core http module.