diffhook

Asynchronous webhooks for monitoring changes in external webpages.

Getting Started

Using diffhook is as simple as the following (using ES6 syntax):

npm i diffhook or yarn add diffhook

import diffhook from 'diffhook';
 
var hook = null;
 
function testFunc(oldResponse, newResponse) {
    console.log("Old Response:");
    console.log(oldResponse);
    console.log("New Response:");
    console.log(newResponse);
    clearInterval(hook);
}
 
var hook = diffhook("https://brandonrninefive.github.io", 10000, testFunc, "Tick");

The above setup will make an AJAX call to https://brandonrninefive.github.io and log the string "Tick" every 10 seconds. However, if a response has not been fully returned from the last AJAX call, or a connection error occurs, the next "Tick" will be logged, but a new AJAX call will not be sent out. Any connection errors will also be logged. testFunc will only be called if the AJAX request is successful, and the contents of the response differs between calls.

diffhook returns a call to setInterval(), meaning the hook can be stopped with clearInterval(), such as in the example above.

Parameters

url - (String) The URL of the webpage to monitor.

interval - (Number) The interval between AJAX calls (in milliseconds).

callback - (Function) The function to execute when a diff occurs between AJAX calls. This function is passed two parameters, oldResponse, and newResponse, representing the last and current contents of the AJAX response, respectfully.

pollingStr - (String) A string to log to the console each time an AJAX call is made. Passing null will prevent any logging.

Interval Courtesy

Since making frequent requests to URLs can throttle the response times of servers, setting interval to be too low could be perceived as a network attack. For this reason, it is highly recommended that you set interval to be a minimum of multiple seconds, or even minutes, in length. If you want to use a smaller interval value, do so at your own risk.