Find the places where certain pattern occur in a string using JS, keeping in mind interpolation and not repeating the result. Is using node :P

Patterns in string

var start = new Date().getTime();
var str="";
var mtc="CTTGATCAT";
var n = " ";
var alr = new Array();
var j = 0;
var url = 'https://beta.stepic.org/media/attachments/lessons/3/Vibrio_cholerae.txt';
var http = require('https');

var fs = require('fs');


function storeOutput(txt){
    fs.writeFile("output.txt", txt , function(err) {
        if(err) {
            console.log(err);
        } else {
            console.log("The file was saved!");
        }
    });
}

function inArray(needle, haystack) {
    var length = haystack.length;
    for(var i = 0; i < length; i++) {
        if(typeof haystack[i] == 'object') {
            if(arrayCompare(haystack[i], needle)) return true;
        } else {
            if(haystack[i] == needle) return true;
        }
    }
    return false;
}


function findPatterns(str){
    str = str.toString();
    for(var i = 0; i < str.length; i++){
        j = str.indexOf(mtc,i);
        console.log(i);
        if( j != -1  && !inArray(j,alr) ){
            alr.push(j);
            n += " " + j;
        }
    }
    var total = j.length;
    console.log( "the pattern was found this many times: " + total );
    var end = new Date().getTime() - start;
    console.log(" it took so many time in the operation " + end );
    return n;
}



function httpGet(theUrl){
    var req = http.get(theUrl,function(res){
        res.on('data',function(chunk){
            str += chunk;
        });
        res.on('end',function(){
            output = findPatterns(str);
            storeOutput(output);
        });
    });
    req.write('data\n');
    req.write('data\n');
    req.end();

}

// httpGet(url);
// now i'm reading a file from disk instead of from a url that took forever
fs.readFile('str.txt', function(err,data){
    console.log(1);
    output = findPatterns(data);
    console.log(2);
    storeOutput(output);
});