JSFiddle - React, Tailwind, and code Playground

JavaScript

function a(){
    var arr = {'one' : 1, 'two' : 2};
    for(var key in arr){
        if(arr.hasOwnProperty(key)){
            window[key] = arr[key];
        }
    }
    alert('1 OK');
};

function b(){
    var arr = {'one' : 1, 'two' : 2};
    for(var key in arr){
        if(arr.hasOwnProperty(key)){
            eval('var ' + key + '='+arr[key]);
        }
    }
    alert('2 OK');
};

function c(){
    var arr = {'one' : 1, 'two' : 2};

    for(var key in arr){
        if(arr.hasOwnProperty(key)){
            this[key] = arr[key];
        }
    }
    alert('3 OK');
};


a();
b();
new c();