Q:

How can I check available RAM in my ionic 3 app? 

Im using extended-device-information plugin to get my mobile ram in ionic 3 application.  But I would like to get available memory(RAM) in my device. 
How to calculate available RAM in ionic 3? 

A:

chrome.system.memory Plugin

It doesn't appear the extended-device-information plug-in can
  calculate the "available memory".  You would likely need to use the
  chrome.system.memory Plugin or similar to accomplish that. 

↳ https://developer.chrome.com/apps/system_memory
extended-device-information Plugin
From the documentation (only shows total memory capacity):
import { ExtendedDeviceInformation } from '@ionic-native/extended-device-information/ngx';

constructor(private extendedDeviceInformation: ExtendedDeviceInformation) { }

...

console.log('The Memory is: ' + this.extendedDeviceInformation.memory);

↳ https://ionicframework.com/docs/native/extended-device-information

