Multithreading in JavaScript?

will help you Web Workers. They’re a W3C standard (well, a working draft at the moment) for exactly this, and require no plugins:

With these it helps As previous answers already stated, WebWorkers are Javascript's only option for multi-threading. Unfortunately, there's no hope if you want to do DOM modifications.
What most people forget is when you call functions with setTimeout and setInterval the UI does not freeze and still receives updates.

function btnClickHandler() {
    setTimeout(doStuff, 1); // prevent UI freeze
}

function doStuff() {
    // do your stuff here
}

var i, interval;

$("#btn1").click(function(){
    i = 0; // reset i

    // create interval
    interval = setInterval(btn1Handler, 1); // run btn1Handler every 1ms
});

function btn1Handler() {
    $("#loop1").html(i);

    if(i++ >= 100000) {
        // cancel the interval
        clearInterval(interval);
    }
}

it should still fix some issue I'm going to assume you're talking about in a web browser.
JavaScript in web browsers has a single main UI thread, and then zero or more web worker threads. Web workers are indeed isolated from the main UI thread (and each other) and so don't have access to globals (other than their own). This is intentional, it makes both implementing the environment and using it dramatically simpler and less error-prone. (Even if that isolation weren't enforced, it's good practice for multi-threaded programming anyway.) You send messages to, and receive messages from, web workers via postMessage and the message event.

help you fix your problem Question 1
You need to create n threads in the same manner as HelloCPP11() and pass i to PieEstimateAux() as a thread ranking variable.