PnP-JS-Core library contains the number of extensible methods and properties. By using that we can achieve the various actions in a simple code. To know more about this library component, visit the below links,

Simplified JavaScript Library for SharePoint

PnP-JS-Core Library

This post explains,

How to get all users from a SharePoint group using PnP JavaScript Library.

Example:

The below steps and code snippet used to get all the users from a given group in SharePoint site using PnP JavaScript library,

  1. Download Required files to use PnP-JS-Core library from the below links and upload that to Site Asstes or Style Library
    • Download pnp.js  PnP JS file
    • Download fetch.js Used by PnP js file to handle web requests and responses (Required in IE)
    • Download promise.js Used by PnP js file to handle web requests and responses (Required in IE)
  2. Create new web part page and insert Content Editor web part
  3. Create a sample.html file in Site Assets or Style library and insert the below code snippet 
    <script type="text/javascript" src="/siteassets/scripts/fetch.js"></script> 
<script type="text/javascript" src="/siteassets/scripts/promise.min.js"></script> 
<script type="text/javascript" src="/siteassets/scripts/pnp.min.js"></script>
  
<div id="sample"></div>

<script type="text/javascript">
//siteGroups.getByName returns the SiteGroup object based on the given group name
//users property returns all users object in an array
//then( ) runs on success
//catch( ) runs on failure
//Replace <Group Name> with the actual group name

$pnp.sp.web.siteGroups.getByName('<Group Name>').users.get().then(function(result) {
    var usersInfo = "";
    for (var i = 0; i < result.length; i++) {
        usersInfo += "Title: " + result[i].Title + " ID:" + result[i].Id + "<br/>";
    }
    document.getElementById("sample").innerHTML = usersInfo;
}).catch(function(err) {
    alert("Group not found: " + err);
});
</script>
  4. Add the URL of sample.html file to the content editor web part
  5. Click ok to apply the changes to the web part and save the page.
  6. Now the page displays a user’s display name and id from a given SharePoint group using PnP JavaScript method .