how to upload image in a webpack+react+express project?

i tried a lot to upload image into my webpack+react+express project, but failed everytime. the database is mongo and i use mongoose for connection. in the express main js file. i wrote: app.use(require('express-formidable')({ uploadDir: path.join(__dirname, '/public/img'), keepExtensions: true })); and in my react file, i also add encType="multipart/form-data" into the form. the funny thing is this: when i put encType="multipart/form-data" into the form, the project won't work and there is an error: Uncaught Error: _registerComponent(...): Target container is not a DOM element.(…) i googled this error and people say this is caused by js file not at bottom in html, but my js file is at the bottom. if i delete encType="multipart/form-data" from the form. everything works fine and i can find the pic info in mongo database. but there is no image uploaded to my project. is this an error with webpack or react? how to solve this problem!