How to locate the js statement that jumps to another web page?

Question

How to locate the js statement that jumps to another web page?

171 Views Asked by William At 11 November 2025 at 09:36

When I open some web pages, they may jump to another web page automatically after a while. For example, if you open https://list.jd.com/list.html?cat=670,677,688 it will jump to cfe.m.jd.com/..., then further jump to passport.jd.com that asks you to login. I think on the page list.jd.com/..., there must be a statement like window.location.href=...that causes the jump. But where is the statement? How can I find the statement in a systematic way? I mean I can press F12 and set a breakpoint on that statement then refresh the page to stop at that statement.

Original Q&A

There are 2 best solutions below

danielRICADO On 07 November 2023 at 21:23

there's a 302 response coming, meaning its a redirect configuration on the server not javascript.

**jQueeny** · Accepted Answer

Not all redirects are done using JavaScript so that means there won't always be a location.href to look for in a script. In fact it's quite the opposite. Most redirects like the one you gave in your example are done on the server, load balancer or most likely by the DNS provider, more explanation here.

If you curl the url in your example you will see there is a 302:

curl -s https://list.jd.com/list.html?cat=670,677,688

<html>
<head><title>302 Found</title></head>
<body bgcolor="white">
<center><h1>302 Found</h1></center>
<hr><center>nginx/1.10.3</center>
</body>
</html>

You can tell curl to follow this redirect with the -L option:

curl -sL https://list.jd.com/list.html?cat=670,677,688

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport"
    content="width=device-width,initial-scale=1.0,user-scalable=no,maximum-scale=1.0,viewport-fit=cover" />
  <title>京东安全</title>
<link href="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/css/app.34c74a0c.css" rel="preload" as="style"><link href="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/js/app.js" rel="preload" as="script"><link href="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/js/chunk-vendors.js" rel="preload" as="script"><link href="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/css/app.34c74a0c.css" rel="stylesheet"></head>

<body>
  <div class="ipaas-floor-app"></div>
<script type="text/javascript" src="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/js/chunk-vendors.js"></script><script type="text/javascript" src="https://cfe.m.jd.com/privatedomain/risk_handler/03101900/js/app.js"></script></body>

There a couple of scipts listed in that response so you could see what is happening in those scripts.

The best way would be to go into your dev tools (for illustration I'll use Chrome) and select:

Sources tab.
On the right-hand side select Event Listener Breakpoints
Load
Now check Load and Unload.

Paste https://list.jd.com/list.html?cat=670,677,688 and see the various stages of the Load and Unload. The browser will pause at these breakpoints. Good luck with your exploration.

How to locate the js statement that jumps to another web page?

There are 2 best solutions below

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