popper.js is used in bootstrap 4.0, but due to network reasons, dropdown may not be able to find popper.js?
dropdown The solution for popper.js cannot be found: How to download popper.js?
In the recent project, bootstrap was upgraded from version 3.3.7 to version 4.0
It was found that dropdown could not find popper.js
Solution: npm install -save popper
After downloading, check the dist directory of the node_modules file
There are two directories in the root directory, one is umd and the other is esm. In addition, there is popper.js# in the root directory.
##If it is the loading method of
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
