为什么这个异步只会在作为函数调用时影响全局变量，而不是在显式写入时？

Question

var http=require('http');
var bl=require('bl');
var strs=[];
var finished=0;

for(var index=2; index<process.argv.length; index++)
{
    var url=process.argv[index];
    //makeRequest(url,index-2); --- This works.
    http.get(url,function (response)  //But if I do this inline, as opposed to making the request as a function, it goes to hell...why?
    {
        response.pipe
        (
            bl
            (
                function(err,data)
                {
                    if(err) throw err;
                    var thisResponse=data.toString();
                    strs[index-2]=thisResponse;  //this is not really happening...why?
                    finished++;
                    if(finished==3)
                    {
                        //it's getting here, but strs is unchanged from the beginning
                        printResults();
                    }
                }
            )
        );
    });
}


function makeRequest(url,index)
{
    http.get(url,function (response)
    {
        response.pipe
        (
            bl
            (
                function(err,data)
                {
                    if(err) throw err;
                    var thisResponse=data.toString();
                    strs[index]=thisResponse;
                    finished++;
                    if(finished==3)
                    {`enter code here`
                        printResults();
                    }
                }
            )
        );
    });
}


function printResults()
{
    for(var j=0; j<3; j++)
    {
        console.log(strs[j]);
    }
}

所以我有这个函数来创建一个http.get请求，然后将响应抛出一个字符串数组。现在，当我调用该函数时，它工作正常，但是当我编写该函数时，（如下所示// makeRequest（url，index-2）;），它不会影响strs []数组，即使一切我正在做的是在异步流程中（我认为）。有人能告诉我为什么会这样吗？