Jitendra Zaa Blog on how to define reusable LWC component to share Javascript code

DemoWrapperLWC.html

<template> 
  ... Some UI related code here
</template>

DemoWrapperLWC.js

import { LightningElement , track } from 'lwc'; 
//Importing reusable LWC Component as Javascript utility
import {getUrlParameter } from 'c/JSUtility';

export default class DemoWrapperLWC extends LightningElement {
   //Some track variables define 
   //...... 
   //.. Some code
  
    //Similar to init method in Aura
    connectedCallback() { 
      //Note - We are NOT using "this" keyword to access method getUrlParameter
      let param1 = getUrlParameter('param1'); 
      console.log('Found Parameter value for param1'+param1);
    }

}

DemoWrapperLWC.js-meta.xml

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>48.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__AppPage</target>
        <target>lightning__RecordPage</target>
        <target>lightning__HomePage</target>
        <target>lightningCommunity__Page</target>
        <target>lightningCommunity__Default</target>
    </targets>
  
</LightningComponentBundle>