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133 lines
5.7 KiB
Markdown
133 lines
5.7 KiB
Markdown
# sync-request
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Make synchronous web requests with cross-platform support.
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> Requires at least node 8
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# **N.B.** You should **not** be using this in a production application. In a node.js application you will find that you are completely unable to scale your server. In a client application you will find that sync-request causes the app to hang/freeze. Synchronous web requests are the number one cause of browser crashes. For production apps, you should use [then-request](https://github.com/then/then-request), which is exactly the same except that it is asynchronous.
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[](https://travis-ci.org/ForbesLindesay/sync-request)
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[](https://david-dm.org/ForbesLindesay/sync-request)
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[](https://www.npmjs.org/package/sync-request)
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## Installation
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npm install sync-request
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## Usage
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```js
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request(method, url, options);
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```
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e.g.
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* GET request without options
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```js
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var request = require('sync-request');
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var res = request('GET', 'http://example.com');
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console.log(res.getBody());
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```
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* GET request with options
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```js
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var request = require('sync-request');
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var res = request('GET', 'https://example.com', {
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headers: {
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'user-agent': 'example-user-agent',
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},
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});
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console.log(res.getBody());
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```
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* POST request to a JSON endpoint
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```js
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var request = require('sync-request');
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var res = request('POST', 'https://example.com/create-user', {
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json: {username: 'ForbesLindesay'},
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});
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var user = JSON.parse(res.getBody('utf8'));
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```
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**Method:**
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An HTTP method (e.g. `GET`, `POST`, `PUT`, `DELETE` or `HEAD`). It is not case sensitive.
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**URL:**
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A url as a string (e.g. `http://example.com`). Relative URLs are allowed in the browser.
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**Options:**
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* `qs` - an object containing querystring values to be appended to the uri
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* `headers` - http headers (default: `{}`)
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* `body` - body for PATCH, POST and PUT requests. Must be a `Buffer` or `String` (only strings are accepted client side)
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* `json` - sets `body` but to JSON representation of value and adds `Content-type: application/json`. Does not have any affect on how the response is treated.
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* `cache` - Set this to `'file'` to enable a local cache of content. A separate process is still spawned even for cache requests. This option is only used if running in node.js
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* `followRedirects` - defaults to `true` but can be explicitly set to `false` on node.js to prevent then-request following redirects automatically.
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* `maxRedirects` - sets the maximum number of redirects to follow before erroring on node.js (default: `Infinity`)
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* `allowRedirectHeaders` (default: `null`) - an array of headers allowed for redirects (none if `null`).
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* `gzip` - defaults to `true` but can be explicitly set to `false` on node.js to prevent then-request automatically supporting the gzip encoding on responses.
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* `timeout` (default: `false`) - times out if no response is returned within the given number of milliseconds.
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* `socketTimeout` (default: `false`) - calls `req.setTimeout` internally which causes the request to timeout if no new data is seen for the given number of milliseconds. This option is ignored in the browser.
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* `retry` (default: `false`) - retry GET requests. Set this to `true` to retry when the request errors or returns a status code greater than or equal to 400
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* `retryDelay` (default: `200`) - the delay between retries in milliseconds
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* `maxRetries` (default: `5`) - the number of times to retry before giving up.
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These options are passed through to [then-request](https://github.com/then/then-request), so any options that work for then-request should work for sync-request (with the exception of custom and memory caching strategies, and passing functions for handling retries).
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**Returns:**
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A `Response` object.
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Note that even for status codes that represent an error, the request function will still return a response. You can call `getBody` if you want to error on invalid status codes. The response has the following properties:
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* `statusCode` - a number representing the HTTP status code
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* `headers` - http response headers
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* `body` - a string if in the browser or a buffer if on the server
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It also has a method `res.getBody(encoding?)` which looks like:
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```js
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function getBody(encoding) {
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if (this.statusCode >= 300) {
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var err = new Error(
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'Server responded with status code ' +
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this.statusCode +
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':\n' +
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this.body.toString(encoding)
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);
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err.statusCode = this.statusCode;
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err.headers = this.headers;
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err.body = this.body;
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throw err;
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}
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return encoding ? this.body.toString(encoding) : this.body;
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}
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```
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## Common Problems
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### Could not use "nc", falling back to slower node.js method for sync requests.
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If you are running on windows, or some unix systems, you may see the message above. It will not cause any problems, but will add an overhead of ~100ms to each request you make. If you want to speed up your requests, you will need to install an implementation of the `nc` unix utility. This usually done via something like:
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```
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apt-get install netcat
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```
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## How is this possible?
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Internally, this uses a separate worker process that is run using [childProcess.spawnSync](http://nodejs.org/docs/v0.11.13/api/child_process.html#child_process_child_process_spawnsync_command_args_options).
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The worker then makes the actual request using [then-request](https://www.npmjs.org/package/then-request) so this has almost exactly the same API as that.
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This can also be used in a web browser via browserify because xhr has built in support for synchronous execution. Note that this is not recommended as it will be blocking.
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## License
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MIT
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