var currentScope = {};
var currentScopeStack = [currentScope];

currentScope.a = 0;
currentScope.b = 0;

function findScopeWithProperty(stack, property) {
    return stack.concat().reverse().find(e => e.hasOwnProperty(property));
}

(function(currentScopeStack) {
    var currentScope = {};
    currentScopeStack.push(currentScope);
    currentScope.a = 1;

    console.log(findScopeWithProperty(currentScopeStack, "a").a); // 1
    console.log(findScopeWithProperty(currentScopeStack, "b").b); // 0
    findScopeWithProperty(currentScopeStack, "b").b = 10;

    (function(currentScopeStack) {
        var currentScope = {};
        currentScopeStack.push(currentScope);
        currentScope.b = 2;
        console.log(findScopeWithProperty(currentScopeStack, "a").a); // 1
        console.log(findScopeWithProperty(currentScopeStack, "b").b); // 2

    })(currentScopeStack.concat())
})(currentScopeStack.concat())

console.log(findScopeWithProperty(currentScopeStack, "a").a) // 0
console.log(findScopeWithProperty(currentScopeStack, "b").b) // 10