JSFiddle - React, Tailwind, and code Playground

JavaScript

var shared_variables = {};

$(document).ready(function () {
    test1.apply(shared_variables);//undefined
    
    test2.apply(shared_variables);
    
    test1.apply(shared_variables);//foo
});

function test1 () {
    alert(this.testvar);
}

function test2 () {
    var a = 'foo';
    this.testvar = a;
}