Property 'cordova' does not exist on type 'Window'. : ionic

That's just Typescript complaining because cordova is not part of the window object definition. There're several ways to avoid that error:

One way is to declare a window property of type any, like this:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

declare let window: any; // <--- Declare it like this

@Component({
  selector: 'page-demo',
  templateUrl: 'demo.html'
})
export class DemoPage {

  constructor(public navCtrl: NavController, ...) { }

  public yourMethod(): void {
    var browserRef = window.cordova.InAppBrowser.open(); // <--- and use it like this
  }

}

Another way would be to cast the window object to be of type any in the same statement where you want to use it:

var browserRef = (<any>window).cordova.InAppBrowser.open();
// or
var browserRef = (window as any).cordova.InAppBrowser.open();

If you don't want to use any you could also define the type of the window object based on the method/s you want to call:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

declare let window: {
  cordova: {
    InAppBrowser: {
      open: () => {};
    }
  }
}

@Component({
  selector: 'page-demo',
  templateUrl: 'demo.html'
})
export class DemoPage {

  constructor(public navCtrl: NavController, ...) { }

  public yourMethod(): void {
    var browserRef = window.cordova.InAppBrowser.open();
  }

}

Cordova executes only on devices, not in browser. The way to avoid errors when viewing your build in a browser is to wrap Cordova commands in a platform if statement. In example:

import { Platform } from 'ionic-angular';
import { InAppBrowser } from '@ionic-native/in-app-browser';

constructor( private platform: Platform, private iab: InAppBrowser ) {
    this.platform.ready().then(function () {
        if (platform.is('cordova')) {
            // your code, eg:
            this.iab.create('http://google.com/', '_blank');
        }
    });
}

Another solution would be to change

window.cordova

to

window['cordova']

In typescript 4, tslint doesn't like the <any> cast anymore.

It seems to now prefer this.

 var browserRef = (window as any).cordova.InAppBrowser.open();