AWS CDN + Lambda#Edge MimeType Issue - amazon-web-services

Question

I've been working lately with AWS CDN + S3 bucket as origin.
When no lambda#edge function attached into the Origin Request it works fine but I need the lambda#edge fn for rerouting. Some of the js file's mimetype are not text/javascript instead text/html. Any idea?
Lambda#edge function is just a simple rerouting no special feature.
Here is the function:
'use strict';
exports.handler = (evt, context, cb) => {
const { request } = evt.Records[0].cf;
const uriParts = request.uri.split("/")[1];
const locales = ['en-US', 'ja', 'ms'];
if (!uriParts || !locales.includes(uriParts)) {
request.uri = '/en-US/index.html';
return cb(null, request)
}
request.uri = `/${uriParts}/index.html`;
console.log(`Request Uri: ${request.uri}`);
cb(null, request);
}
Sample response image
Setup:
S3 Bucket
en-US/
index.html
<bunch of js files from angular>
ja/
index.html
<bunch of js files from angular>
ms/
index.html
<bunch of js files from angular>
CDN Distribution + Origin is the S3

Answer 1

Solved. First of all, my bad for not understanding well the triggers of Lambda#Edge function. Refer to this article.
First try, I used origin request as s trigger and somehow came to understand that it wasn't I need for my case.
After some debug and reading, I used viewer request this time. Also, alter my Lambda#Edge function to this.
'use strict';
const path = require("path");
exports.handler = async (evt,context,cb) => {
const { request } = evt.Records[0].cf;
console.log(`Original Uri: ${request.uri}`);
const uriParts = request.uri.split("/");
const locale = uriParts.length > 1 ? uriParts[1] : "";
const locales = ["en-US", "ja", "ms"];
if (locale === "" || locale === "index.html") {
request.uri = "/en-US/index.html";
return cb(null, request);
}
if (!locales.includes(locale)) return cb(null, request);
const lastPartUrl = uriParts[uriParts.length - 1];
const fileExt = path.extname(lastPartUrl);
if (!fileExt) request.uri = `/${locale}/index.html`;
console.log(`New Uri: ${request.uri}`);
return cb(null, request);
};
Now every locale in our application is now working fine.