Echo.ts checks for globals instead of properties installed on the window object

[kylestev]

Background

Laravel 5.3's default javascript scaffolding requires resources/assets/js/bootstrap.js at the top of the resources/assets/js/app.js file. The bootstrap.js file has side effects when required that mutates the window object due to the way that the vue and vue-resource packages install themselves globally.

Side effects

Package	Side Effect
vue	Installs property Vue onto window
vue-resource	Installs property http onto window.Vue

Issue

The issue here is that this library is checking for a global instead of a property on the window. This becomes apparent when using this library without bootstrap.js scaffolding shipped with Laravel 5.3.