I'm trying to import a 3rd party javascript library from static resources in my lightning web component. I followed the exemple given in LWC documentation.

I encounter the folowing error :

Uncaught (in promise) TypeError: Cannot read property 'Symbol(ViewModel)' of undefined

Uncaught (in promise) TypeError: m is not a function

My sample code :

import loadScript from 'lightning/platformResourceLoader';
import fuse from '@salesforce/resourceUrl/fuse';

export default class SelectActivity extends LightningElement {

    fuseLoaded = false;

    renderedCallback() {
            loadScript(this,fuse + "/fuse.js")
                .then( () => {
                    this.fuseLoaded = true;
                .catch( error => console.log(error));



And my static resource is present :

Static resource

Thank you in advance

3 Answers 3


You are passing a path variable in your loadScript call (/fuse.js) which is required when you want to load a file inside an archive When you upload the javascript file directly (which is the case based on your screenshot) you only pass the import identifier as 2nd argument

  • and then there is also the fact that the library might not be locker service compliant, which might lead to other/similar issues after =/
    – glls
    Jul 16, 2019 at 11:34
  • Hello, thank you for both of your answers. I tried using @Renji-XD's line but it gives me the same error. Furthermore, I don't think that the issue is with Locker Service compliance because a colleage of mine uses this lib in Aura Components without problem.
    – Ombrelin
    Jul 17, 2019 at 9:21
  • that means nothing - i also already encountered stuff which works fine in aura but not in lwc. I tried your lib (assuming it is fusejs.io) and got no error.so i can`t really give any further hints as from my side everything looks ok
    – Renji-xD
    Jul 17, 2019 at 13:12
  • I finally got it to work the problem was that the imported fuse varaible wasn't seen, I had to create a field in my controller class and assin the imported value to it.
    – Ombrelin
    Jul 22, 2019 at 14:32

As said above, loadScript(this,fuse) should work fine.

Adding to it, you should not load script in renderedCallback as it will be invoked for every api/track variable change (unless it needs to like in case of graph where graph changes with every parameter change). You should be using connectedCallback instead.


I was able to solve this by removing the promise part from the loadScript. This below code only is enough as earlier answered by @salesforce-sas


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