Why do I see network requests at in Chrome broswer?

[yangjunfocus]

I'm submitting a ... (check one with "x")

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  <!-- Please check the repository for a similar issue or PR before submitting -->
[ ] Support request => <!-- Please check the repository for a similar issue or PR before submitting -->
[ ] Feature request
[ ] Documentation issue or request

Current behavior

Expected/desired behavior

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Environment

• Angular version: X.Y.Z

• Browser:

• [x] Chrome (desktop) version XX
• [ ] Chrome (Android) version XX
• [ ] Chrome (iOS) version XX
• [ ] Firefox version XX
• [ ] Safari (desktop) version XX
• [ ] Safari (iOS) version XX
• [ ] IE version XX
• [ ] Edge version XX

• For Tooling issues:

• Node version: XX <!-- run node --version -->
• Platform:

• Others: