XHR Module

The XHR module enables the developer to send HTTP or HTTPS requests to a remote web server and load the response data back into the Event Handler (EH).

Common applications include accessing 3rd party web services and triggering webhooks.

Note
  1. The maximum recursion limit you can do is 3 - hops from one Function to another, using publish or fire, you can execute a maximum of three Functions.
  2. The combined maximum number within a single Function execution of KV store operations, XHRs, publish and fire is 3.

The XHR module is made available via the following require statement:

const xhr = require("xhr");

Get

For vanilla GET calls, use the XHR.fetch() method:

xhr.fetch("https://neutrinoapi.com/geocode-address").then((serverResponse) => {
    // handle server response
}).catch((err) => {
    // handle request failure
});

XHR Timeout

XHR module has a timeout option with a default value of 5,000 and maximum value of 10,000 milliseconds.

Note

Socket hang up error in function means that the function is making an outgoing connection to a remote server and that the remote server has abruptly closed the socket.

Example

export default (request) => {
    const xhr = require("xhr");
    const http_options = {
        "timeout": 5000, // 5 second timeout.
        "method": "POST",
        "body": "foo=bar&baz=faz"
    };

    const url = "http://httpbin.org/post";

    return xhr.fetch(url, http_options).then((x) => {
        const body = JSON.parse(x.body);
        console.log(body);
        return request.ok();
    });

};

Comprehensive HTTP Method Support:

GET, POST, PUT, OPTIONS, DELETE, PATCH

In addition to GET requests, we can also make POST, PUT, OPTIONS, DELETE, and PATCH requests; just include a method attribute with the appropriate verb as the value in the httpOptions variable.

For example, to POST or PUT:

export default (request) => {
    const xhr = require("xhr");
    const http_options = {
        "method": "POST", // or PUT
        "body": "foo=bar&baz=faz"
    };

    const url = "http://httpbin.org/post";

    return xhr.fetch(url, http_options).then((x) => {
        const body = JSON.parse(x.body);
        console.log(body);
        return request.ok();
    });

};

For methods like POST or PUT that require sending a JSON data payload, be sure to set the headers, and the body attributes in the HTTP options parameter.

export default (request) => {
    const xhr = require("xhr");
    const http_options = {
        "method": "POST",
        "headers": {
            "Content-Type": "application/json"
         },
        "body": JSON.stringify({
            "body": "Posting JSON!",
            "to": "Someone Special!"
        })
    };

    const url = "http://httpbin.org/post";

    return xhr.fetch(url, http_options).then((x) => {
        const body = JSON.parse(x.body);
        console.log(body);
        return request.ok();
    });
};

Sending form data also uses the POST method, but with the application/x-www-form-urlencoded content type.

export default (request) => {
    const xhr = require("xhr");
    const http_options = {
        "method": "POST",
        "headers": {
            'Content-Type': 'application/x-www-form-urlencoded',
        },
        "body": "foo=bar&z=x&abc=123"
    };

    const url = "http://httpbin.org/post";

    return xhr.fetch(url, http_options).then((x) => {
        const body = JSON.parse(x.body);
        console.log(body);
        return request.ok();
    });
};
Note

PubNub Functions provides a rich set of tools, and this documentation does not cover all of the potential situations you may encounter. If you need help with a situation not covered by the documentation, please contact PubNub Support

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