[javascript] Excel to JSON javascript code?

@Kwang-Chun Kang Thanks Kang a lot! I found the solution is working and very helpful, it really save my day. For me I am trying to create a React.js component that convert *.xlsx to json object when user upload the excel file to a html input tag. First I need to install XLSX package with:

npm install xlsx --save

Then in my component code, import with:

import XLSX from 'xlsx'

The component UI should look like this:

<input
  accept=".xlsx"
  type="file"
  onChange={this.fileReader}
/>

It calls a function fileReader(), which is exactly same as the solution provided. To learn more about fileReader API, I found this blog to be helpful: https://blog.teamtreehouse.com/reading-files-using-the-html5-filereader-api