I was trying to import image using:
import image from 'image.jpeg';
the following error pops out.
Failed to load module script: The server responded with a non-JavaScript MIME type of "image/jpeg". Strict MIME type checking is enforced for module scripts per HTML spec.
in my index.html, I imported my main script file as:
<script src="index.js" type="module"></script>
then in the index.js:
import image from 'image.jpeg';
When I run it using Chrome, it results in the above-mentioned error. Any help?
JavaScript running in a web browser can only import JavaScript modules and (thanks to the new import assertions feature), with limited browser support, JSON.
There are tools (such as WebPack) which can import images, but you aren't using one of them.
I'm making a Chrome extension and I'm trying to import a Typescript file in Javascript.
Both files are next to each others.
I'm importing it this way:
import { ApiParsing } from './ApiParsing.ts';
When I'm using the extension I have the following error:
Failed to load module script: The server responded with a non-JavaScript MIME type of "". Strict MIME type checking is enforced for module scripts per HTML spec.
TypeScript cannot be executed from a browser / node.js environment directly. At first you have to transpile it into native javascript. To do this you will need to execute tsc.
https://www.typescriptlang.org/docs/handbook/compiler-options.html
https://www.typescriptlang.org/docs/tutorial.html
Typescript is a so called "Superset" of JavaScript which means that all typescript code will be transpiled into usual JS code from the typescript compiler. Often those compile processes are linked with a bundler like webpack.
https://webpack.js.org/concepts/
Knowing this your error The server responded with a non-JavaScript MIME type makes a lot of sense due to a typescript file is a "non-JavaScript MIME type".
Note:
You can't import typescript files into javascript files, but you can do it vice versa.
You can do that through babel. Follow below article
Article: How to use typescript file in javascript project
I am trying to make a Rust WebAssembly project and have modified the rust-webpack-template as my starting point. The template is a webpack project with a JavaScript file that calls a single Wasm function and the Rust Wasm takes over from there.
I have modified the template because I would like to have my main logic in JavaScript and call the Rust Wasm through an API.
I have changed the webpack entry to bootstrap.js shown below.
// bootstrap.js
import("./index.js").catch(e =>
console.error("Error importing 'index.js':", e)
);
I added the file index.js and it calls the Rust Wasm functions
// index.js
import * as wasm from "../crate/pkg/rust_webpack";
const title = document.getElementById("msg");
title.innerText = wasm.get_msg();
The get_msg function from Rust looks like this:
#[wasm_bindgen]
pub fn get_msg() -> String {
"Hello from Rust WebAssembly!".to_owned()
}
When I run the project using webpack-dev-server -d, everything works fine.
However, when I build the project using webpack and try and host the generated files directly, nothing is displayed and the browser console displays the error:
Error importing 'index.js': TypeError: "Response has unsupported MIME type"
This error comes from the code in bootstrap.js but I'm not entirely sure what it means or how to fix this error.
Why do things work when serving with the webpack dev server but not after bundling everything together?
As Shepmaster helped me to figure out in the comments, the MIME type of the .wasm file is being set to application/octet-stream when the browser expects it to be application/wasm.
I am using a simple express server to host my files. Express can be configured to use the correct MIME type with a single line.
var express = require('express');
var app = express();
// Set the MIME type explicitly
express.static.mime.define({'application/wasm': ['wasm']});
app.use(express.static('./dist'));
app.listen(3000);
According to this issue, express will handle .wasm files correctly after version 4.17. It works correctly in webpack dev server because they implemented their own workaround while they wait for the fix in express.
I had a similar problem ("Response has unsupported MIME type") with Flask. The problem was that I didn't have a separate route to the .wasm file. For example:
#app.route('/path/to/file.wasm')
def wasm_file():
return send_file('/path/to/file.wasm', mimetype = 'application/wasm');
It is not the answer to this question, but it's a hint for other people who have a similar problem.
I also encountered this problem, leading me to change my .htaccess file (I'm using Apache to host my local server) to include the following:
AddType application/wasm wasm
If the error persists, and you are getting this error from using WebAssembly.instantiateStreaming, this related question may have an explanation and workaround: WebAssembly InstantiateStreaming Wrong MIME type
Alright, I have looked on this site and have found several different answers, none of which have worked for me.
Basically had a js file that had many functions in it along with the main code for the app. I wanted to move all my functions to another js file so that I could clean up my code a little. I am fairly new to js but I know in python it was as simple as saying "import (module) as (nickname) from (path)"
anyways let's say I have a function named show message in my functions.js module.
export function show_message(){
alert("Hello");
}
and then I at the top of my main.js file I did
import { show_message } from './functions.js'
//I have also tried to import like this:
import * as func from './functions.js'
//And then I call it
show_message();
//I have also tried
func.show_message();
I know this is something simple, but as I said everywhere I have looked I have seen different answers, none of which work for me. I am using Firefox btw. I am also getting an error in the console saying that my import declarations need to be at the top of my module, I fixed that by specifying the type in my HTML link (script src="/static/main.js" type="module")
The error went away but is now saying "same origin policy disallows reading the remote resource at the file (path) (reason: cors request not HTTP)."
And the other error says "module source URI is not allowed in this document".
which makes me think maybe my syntax for importing is right and the error is in my HTML code?
Any help is appreciated.
0. The short answer
You need to install and run a local web server. - For a suggestion on how,
read on.
1. The basics
I tried a simple HTML file – index.html – as follows:
<!-- index.html - minimal HTML to keep it simple -->
<html>
<head>
<meta charset="UTF-8">
<link rel="shortcut icon" href="#">
</head>
<body>
<h1>Hello world!</h1>
<p>Experimenting with JavaScript modules.</p>
<script type="module" src="js/functions.js"></script>
</body>
</html>
In the subfolder js I put the JavaScript file functions.js:
// js/functions.js
alert('Hello');
When double-clicking index.html, my default web browser – Firefox 89.0
(64-bit) – shows the following, after pressing F12.
Notice how the JavaScript code is not running:
The error message:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at file:///C:/stackexchange/reproduce/jsModule/moduleNW/basics/js/functions.js. (Reason: CORS request not http).
A cheating "solution" is to (temporarily) remove type="module" from the HTML
code.
The alert then displays without errors.
But I want to run the JavaScript code as a module, so I put back
type="module" in the HTML.
2. Install and run a local web server
To run it as a module, it needs to run on a web server.
Thus, if you want to run the code on your own computer, you will need to
(install and) start a local web server.
One currently popular alternative is live-server.
Here is what worked for me.
Open a terminal. (On Windows: cmd.exe.)
Type npm and hit Enter to see if Node.js is installed.
If you get command not found, download at https://nodejs.org/en/download/
and install. 1
(On Ubuntu, you can try sudo apt install -y nodejs.)
Install live-server: npm install live-server -g.
Change directory to where your page lives: cd <path-to-index.html>.
Start the server: live-server .
(Should open localhost:8080 in your default browser and show the alert.
See below.)
Note 1.
I am on Windows 10, but the above instructions should work fine on Linux and
macOS too.
Note 2.
Here I used Firefox 89.0, but I have tried Google Chrome 91.0 as well.
The only notable difference is the CORS error message, which in Chrome reads:
Access to script at 'file:///C:/stackexchange/reproduce/jsModule/basics/js/functions.js' from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, chrome-untrusted, https.
3. Exporting and importing
Next I create a new folder demo2 containing the following demo2.html:
<!-- demo2.html - even shorter HTML for simplicity -->
<body>
<h1>Hello world!</h1>
<p>Javascript modules.</p>
<script type="module" src="js/main.js"></script>
</body>
I also create the following three JavaScript files in the subfolder js:
// js/module1.js
export function hi () { console.log('Hi from module 1.'); }
and
// js/module2.js
export function howdy () { console.log('Howdy from module 2!'); }
and
// js/main.js
import { hi } from './module1.js';
import { howdy } from './module2.js';
hi();
howdy();
Now I run live-server from the terminal in the folder where demo2.html
resides.
This time I start by typing
live-server --port=1234 --entry-file=demo2.html
and hitting Enter. Screenshot:
References:
Installing Node.js live-server
The live-server docs
Live-server can't find the file specified
Export and Import
1 On Windows 10, I once needed to
repair the installation.
On the script tag you are using to load the js in the browser you need to add the attribute
type="module"
It will look like the following:
<script type="module">
import {addTextToBody} from './utils.mjs';
addTextToBody('Modules are pretty cool.');
</script>
utils.mjs:
export function addTextToBody(text) {
const div = document.createElement('div');
div.textContent = text;
document.body.appendChild(div);
}
This is if you are not using a bundler like webpack and working directly in the browser.
Source of code: https://jakearchibald.com/2017/es-modules-in-browsers/
You might want to use broswerify instead. It allows you to write NodeJS-style modules and then compiles them into a single browser-friendly JavaScript file, allowing you to get all the performance benefits of loading only a single file. It also means you can easily use the same code both server side and client side.
If you want to stick with separate files, it looks like you are well on your way. Unlike regular JavaScript files, modules are subject to Cross-Origin Resource Sharing (CORS) restrictions. They have to be loaded from the same origin, and cannot be loaded from the local filesystem. If you are loading them from the local file system, move them to a server. If you are already hosting them on a server, add the Access-Control-Allow-Origin: * header to the response that serves the module file.
Lots more gotchas and solutions here and here.
function show_message(){
alert("Hello");
}
export { show_message };
and
import { show_message } from './functions'
i think this should do the trick. this is a named export/import technique. you can under this name find more information if you desire it.
Shortcut for Accepted answer
In case you are using Visual Studio Code just install the Live Preview extension by Microsoft.
In any HTML file click the Show preview icon. It will automatically run a local server and show up in the code editor. After every edit you make it refreshes. You can also show it in your default browser.
No need for command line anymore!
JavaScript has had modules for a long time. However, they were implemented via libraries, not built into the language i.e. you can't import or export part of those modules into your js files (whole library needs to be loaded). ES6 is the first time that JavaScript has built-in modules.
Please refer Here for more info about ES modules.
But things have changed and ES modules are now available in browsers! They're in…
Safari 10.1+, Chrome 61+, Firefox 60+, Edge 16+, etc,.
Now, you need to create your JS file using a new extension .mjs, like,
// utils.mjs
export function addTextToBody(text) {
const div = document.createElement('div');
div.textContent = text;
document.body.appendChild(div);
}
and then, you can import that file into your html page like,
<script type="module">
import {addTextToBody} from './utils.mjs';
addTextToBody('Modules are pretty cool.');
</script>
Please refer Here for more info about using ES module in browsers.
Consider going through this url some extension might be causing an issue with the loading of modules:
This blog might be an answer to what you're expecting.
You should first check if browser accepts type="module" and use fallback if it doesn't like this:
<script type="module" src="module.mjs"></script>
<script nomodule src="fallback.js"></script>
This might be the main reason for the CORS error as written here:
Unlike regular scripts, module scripts (and their imports) are fetched
with CORS. This means cross-origin module scripts must return valid
CORS headers such as Access-Control-Allow-Origin: *
So you need to add CORS header to the module file
Consider this blog for CORS issue. You should add CORS header ie. Access-Control-Allow-Origin: * to the server config most probably.
Using JS modules in the browser
On the web, you can tell browsers to treat a element as a module by setting the type attribute to module.
<script type="module" src="main.mjs"></script>
<script nomodule src="fallback.js"></script>
More on
https://developers.google.com/web/fundamentals/primers/modules
If you're using webpack and babel and want to import the code into your bundle, I guess it should be one of the following:
export default function show_message(){
alert("Hello");
}
and then in your code:
import show_message from 'path/to/show_message.js'
// or
import { default as someOtherName } from 'path/to/show_message.js'
Or if you'd like to export several functions:
const show_message = function(){
alert("Hello");
}
export { show_message };
and then in your code:
import { show_message } from 'path/to/show_message.js'
// or
import { show_message as someOtherName } from 'path/to/show_message.js'
Hope that helps.
I know this old thread but I just fixed this problem myself by using Parcel to launch my website Parcel index.html, in my situation I was using Live server and it didn't work until I switched to parcel .
Instead of using .js, try using .mjs.
Let's say your module file is /modules/App.js, just change it to /modules/App.mjs.
And ofcourse, make sure you have added type="module" in script tag, like this - <script type="module" src="./index.js" defer></script>
My folder structure -
index.html
index.js
modules/App.mjs
This worked for me!
I am creating an single page app in vanilla JavaScript. I want to organize my code in different files to make it modular, which means I should be able to access functions defined in one file in another file. I am using ES6 native import export for this:
file-1.js:
export function func1() {}
export function func2() {}
file-2.js:
import { func1, func2 } from './file-1';
index.html:
<script src="file-1.js"></script>
When I run index.html in Chrome (version 65), I get the following error:
Uncaught SyntaxError: Unexpected token {.
What's wrong in my code? Chrome 65 fully supports ES6 module system.
Here is a working example
file1.mjs
function log1() {
console.log('log1');
}
function log2() {
console.log('log2');
}
export { log1, log2 };
file2.mjs you must explicitly write .mjs extension
import { log1, log2 } from './file1.mjs';
log1();
log2();
index.html Notice attribute type="module"
<body>
<script type="module" src="file2.mjs"></script>
</body>
Then you need a static server to get rid of CORS block.
$ yarn global add serve
$ serve ./
Finally go to http://localhost:5000 and it will work
Update: It is recommended to use .mjs file extension for modules instead of .js
Chrome (v70) has some kind of issues when working with import syntax on the local files served using file protocol. It is probably CORS blocking that can happen using file protocol according to some articles. But Chrome also does not show CORS warning in the console in this case - which is strange. Therefore some kind of HTTP server is needed so the files are served via HTTP protocol (as Vu showed in his answer). Firefox v63 (probably >v60) doesn't have these issues and you can compose html with js modules using file:// protocol without a special server.
Also make sure to:
use file type extensions when importing (import { func1, func2 } from './file-B.js';).
use type="module" in html script element (<script type="module" src="file-A.js"></script>)