Use JavaScript to intercept data received in a webpage

Question

I have a webpage that will receive data in JSON format for every x minutes. I want to get its URL and content.

Manually I can do by using Network tab in Chrome DevTools to view it and copy its respond.

But my question is how do I make it intercept the file automatically. May someone guides me? Thanks.

score 1 · Accepted Answer · answered Aug 09 '18 at 17:31

1

Monkey patch?

XMLHttpRequest.prototype.open = (function(fopen){
    return function(){
        //do something, intercept here
        return fopen.apply(this,arguments); 
    }
})(XMLHttpRequest.prototype.open)

answered Aug 09 '18 at 17:31

ibrahim tanyalcin

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Thanks, the code does execute when new data received. But how do I get its data(respond)? – phwt Aug 09 '18 at 17:39
1

this.responseText OR this.response based on what the responseType was. I advise you thoroughly look at this link: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest – ibrahim tanyalcin Aug 09 '18 at 17:43
you check the response within the onload handler. – ibrahim tanyalcin Aug 09 '18 at 17:44
Can `XMLHttpRequest.response` be used? – phwt Aug 09 '18 at 17:57
not like that, that property is not directly on the constructor, its on the instance => `var x = new XMLHttpRequest; x.onload = function(){....this.response...}` – ibrahim tanyalcin Aug 09 '18 at 18:50

Use JavaScript to intercept data received in a webpage

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