Extend multiple interfaces in LWC

Question

I am trying to extend multiple components in LWC js. but it is not working

I want to extend OmniscriptBaseMixin(LightningElement) and NavigationMixin(LightningElement)

import { LightningElement, api, track } from 'lwc';
import { OmniscriptBaseMixin } from 'vlocity_cmt/omniscriptBaseMixin';
import { NavigationMixin } from 'lightning/navigation';

export default class TestLWC extends OmniscriptBaseMixin(LightningElement), NavigationMixin(LightningElement) {

}

Answer 1

Implementing multiple mixin classes in LWC is handled by nesting them in the extends clause. For your case simply use:

export default class TestLWC extends OmniscriptBaseMixin(NavigationMixin(LightningElement)) 

Answer 2

It might be useful to note that you can also use Object.assign() to extend your JS class. I think this is much cleaner and human readable. Here is an in-depth explanation.