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I'm using ArcGIS JSAPI 4.12 and wish to use
Spatial Illusions
to draw military symbols on a map.
When I add
milsymbol.js
to the script, the console returns error
Uncaught SyntaxError: Cannot use import statement outside a module`
so I add
type="module"
to the script, and then it returns
Uncaught ReferenceError: ms is not defined
Here's my code:
<link rel="stylesheet" href="https://js.arcgis.com/4.12/esri/css/main.css">
<script src="https://js.arcgis.com/4.12/"></script>
<script type="module" src="milsymbol-2.0.0/src/milsymbol.js"></script>
<script>
require([
"esri/Map",
"esri/views/MapView",
"esri/layers/MapImageLayer",
"esri/layers/FeatureLayer"
], function (Map, MapView, MapImageLayer, FeatureLayer) {
var symbol = new ms.Symbol("SFG-UCI----D", { size: 30 }).asCanvas(3);
var map = new Map({
basemap: "topo-vector"
var view = new MapView({
container: "viewDiv",
map: map,
center: [121, 23],
zoom: 7
</script>
So, whether I add type="module" or not, there are always errors. However, in the official document of Spatial Illusions, there isn't any type="module" in the script. I'm now really confused. How do they manage to get it work without adding the type?
File milsymbol.js
import { ms } from "./ms.js";
import Symbol from "./ms/symbol.js";
ms.Symbol = Symbol;
export { ms };
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It looks like the cause of the errors are:
You're currently loading the source file in the src directory instead of the built file in the dist directory (you can see what the intended distributed file is here). This means that you're using the native source code in an unaltered/unbundled state, leading to the following error: Uncaught SyntaxError: Cannot use import statement outside a module. This should be fixed by using the bundled version since the package is using rollup to create a bundle.
The reason you're getting the Uncaught ReferenceError: ms is not defined error is because modules are scoped, and since you're loading the library using native modules, ms is not in the global scope and is therefore not accessible in the following script tag.
It looks like you should be able to load the dist version of this file to have ms defined on the window. Check out this example from the library author to see an example of how this can be done.
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I resolved my case by replacing import with require:
// import { parse } from 'node-html-parser';
const parse = require('node-html-parser');
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There are several common ways to resolve the conflict associated with the above issue
1. The first: In the script, include type=module
<script type="module" src="milsymbol-2.0.0/src/milsymbol.js"></script>
This is the most recommended way to fix the issue
By adding the type="module" attribute, you are telling the browser that the script should be treated as an ECMAScript module, and it should use the appropriate rules for resolving dependencies and executing the code.
2. The second: In node.js, into your package.json file
"type": "module",
Restart the project npm start
3. The third: replace import by require()
Try this
import { parse } from 'node-html-parser';
parse = require('node-html-parser');
Else try this
// import { parse } from 'node-html-parser';
parse = require('node-html-parser');
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I was also facing the same issue until I added the type="module" to the script.
Before it was like this
<script src="../src/main.js"></script>
And after changing it to
<script type="module" src="../src/main.js"></script>
It worked perfectly.
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Applicable for node 12. This answer is no longer maintained for new node versions. Feel free to comment solutions for more recent versions.
I solved this issue by doing the following:
When using ECMAScript 6 modules from the browser, use the .js extension in your files, and in the script tag add type = "module".
When using ECMAScript 6 modules from a Node.js environment, use the extension .mjs in your files and use this command to run the file:
node --experimental-modules filename.mjs
Edit: This was written when node12 was the latest LTS, this does not apply to node 14 LTS.
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I don't know whether this has appeared obvious here. I would like to point out that as far as client-side (browser) JavaScript is concerned, you can add type="module" to both external as well as internal js scripts.
Say, you have a file 'module.js':
var a = 10;
export {a};
You can use it in an external script, in which you do the import, eg.:
<!DOCTYPE html><html><body>
<script type="module" src="test.js"></script><!-- Here use type="module" rather than type="text/javascript" -->
</body></html>
test.js:
import {a} from "./module.js";
alert(a);
You can also use it in an internal script, eg.:
<!DOCTYPE html><html><body>
<script type="module">
import {a} from "./module.js";
alert(a);
</script>
</body></html>
It is worthwhile mentioning that for relative paths, you must not omit the "./" characters, ie.:
import {a} from "module.js"; // this won't work
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If you want to use import instead of require() for modules, change or add the value of type to module in package.json file
Example:
package.json file
"name": "appsample",
"version": "1.0.0",
"type": "module",
"description": "Learning Node",
"main": "app.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
"author": "Chikeluba Anusionwu",
"license": "ISC"
import http from 'http';
var host = '127.0.0.1',
port = 1992,
server = http.createServer();
server.on('request', (req, res) => {
res.writeHead(200, {"Content-Type": "text/plain"});
res.end("I am using type module in package.json file in this application.");
server.listen(port, () => console.log(
'Listening to server ${port}. Connection has been established.'));
For me, it was caused by not referencing a library (specifically typeORM, using the ormconfig.js file, under the entities key) to the src folder, instead of the dist folder...
"entities": [
"src/db/entity/**/*.ts", // Pay attention to "src" and "ts" (this is wrong)
instead of
"entities": [
"dist/db/entity/**/*.js", // Pay attention to "dist" and "js" (this is the correct way)
I got this error in React and fixed it with the following steps:
Go to the project root directory, and open the Package.json file for editing.
Add "type":"module";
Save it and restart the server.
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I'm coding on vanilla JavaScript. If you're doing same, simply add a type="module" to your script tag.
That is, previous code:
<script src="./index.js"></script>
Updated code:
<script type="module" src="./index.js"></script>`
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Why this occurs and more possible causes:
A lot of interfaces still do not understand ES6 JavaScript syntax/features. Hence there is need for ES6 to be compiled to ES5 whenever it is used in any file or project.
The possible reasons for the SyntaxError: Cannot use import statement outside a module error is you are trying to run the file independently. You are yet to install and set up an ES6 compiler such as Babel or the path of the file in your runscript is wrong/not the compiled file.
If you will want to continue without a compiler, the best possible solution is to use ES5 syntax, which in your case would be var ms = require(./ms.js);. This can later be updated as appropriate or better still set up your compiler and ensure your file/project is compiled before running and also ensure your run script is running the compiled file usually named dist, build or whatever you named it and the path to the compiled file in your runscript is correct.
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I have faced the same error by EXPO.
Mainly the solution is that to add "type": "module", in the package.json file.
However, you have to check that which is your correct package.json.
In my case, there are two package.json files, then you should add that to the server file.
To identify which is correct package.json, find "scripts": { "test": "echo \"Error: no test specified\" && exit 1" },
Below ↑ this line, add "type": "module",
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The error is triggered because the file you're linking to in your HTML file is the unbundled version of the file.
To get the full bundled version you'll have to install it with npm:
npm install --save milsymbol
This downloads the full package to your node_modules folder.
You can then access the standalone minified JavaScript file at node_modules/milsymbol/dist/milsymbol.js
You can do this in any directory, and then just copy the below file to your /src directory.
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Use this code. It worked well for me:
Add this script tag to file index.html:
<script type="module">
import { ms } from "./ms.js";
import Symbol from "./ms/symbol.js";
</script>
I ran into this error while trying to use import Express.js.
Instead of import express from 'express';
I used const express = require('express');
None of the provided answers worked for me, but I found a different solution from: How to enable ECMAScript 6 imports in Node.js
Install ESM:
npm install --save esm
Run with ESM:
node -r esm server.js
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I had to import some data from an external file (JavaScript file), to my script.js file present in my HTML file.
File data.js
const data = {a: 1, b: 2}
By adding type=module I got CORS error.
I found out that I can import file data.js into my script.js file just by including file data.js inside my HTML file.
For example, previously my HTML file consists of
<script src="assets/script.js"></script>
As I required some data from file data.js, I just changed my HTML file to:
<script src="assets/data.js"></script>
<script src="assets/script.js"></script>
I.e., include file data.js before file script.js, giving access to my data variable inside file script.js.
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Well, in my case, I didn't want to update my package.json file and change the file type to mjs.
So I was looking around and found out that changing the module in file tsconfig.json affected the result. My ts.config file was:
"compilerOptions": {
"target": "es2020",
"module": "es2020",
"lib": [
"es2020",
"skipLibCheck": true,
"sourceMap": true,
"outDir": "./dist",
"moduleResolution": "node",
"removeComments": true,
"noImplicitAny": true,
"strictNullChecks": true,
"strictFunctionTypes": true,
"noImplicitThis": true,
"noUnusedLocals": true,
"noUnusedParameters": true,
"noImplicitReturns": true,
"noFallthroughCasesInSwitch": true,
"allowSyntheticDefaultImports": true,
"esModuleInterop": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"resolveJsonModule": true,
"baseUrl": "."
"exclude": [
"node_modules"
"include": [
"./src/**/*.ts"
Like this and changing the module from "module": "es2020" to "module" : "commonjs" solved my issue.
I was using MikroORM and thought maybe it doesn't support any module above CommonJS.
I thought I would add this note because it was not apparently obvious to me. You need to add type="module" to all script includes, not just the one you want to use for your utility file.
index.html:
<script type="module" src="js/controllers/utils.js"></script>
<script type="module" src="js/controllers/main.js"></script>`
main.js:
import myFunction from './utils.js
utils.js:
export default myFunction
if you want to import functions from module.
let's say, main.js has func1 and func2 defined, and you want to import those to function to a new module say, test.js
Below will solve the problem.
main.js:
const func1 = () => {console.log('do sth in func1')};
const func2 = () => {console.log('do sth in func2')};
//at the end of module
//export specific functions here
module.exports = { func1, func2 };
test.js :
// import them here
const{ func1, func2} = require('./main.js');
func1();
func2();
Following worked, inline export gave issue but export at the end of fn following worked.
const xxx = async(....)
module.exports = {
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if you are facing same issue in cucumber type script framework then below fix is working.
in cucumber.json file mention as below. install the ts-node
"default":{
"requireModule":[
"ts-node/register"
I've added this in the tsconfig.json and it fixed it .
I was having this issue when trying to run the mockttp !
"ts-node": {
"compilerOptions": {
"module": "commonjs"
