Boyer–Moore string-search algorithm

var s = WScript.StdIn.ReadLine();
var t = WScript.StdIn.ReadLine();
var ans = [];
count = 0;
S_i = 0; // s.charAt(i+j) // should change the name
//j = t.length -1; // t.charAt(j)

sign = {}; // ассоциативный массив
for (i = 0; i<t.length;i++) // подсчет количества повторов
{
    if (CheckIfContainsInT(sign, t.charAt(i)))
    {
        sign[t.charAt(i)]++;
    }
    else
        sign[t.charAt(i)] = 1;
}
Check(sign);

while(S_i<=s.length-t.length) // last symbol
{
    if (s.charAt(S_i+t.length-1) != t.charAt(t.length-1))
    {
        //WSH.echo(s.charAt(S_i+t.length-1) + "!=" + t.charAt(t.length-1));
        //WSH.echo(CheckIfContainsInT(sign, s.charAt(S_i+t.length-1)));
        //WSH.echo(FindLastPosition(t, s.charAt(S_i+t.length-1)));
        if (CheckIfContainsInT(sign, s.charAt(S_i+t.length-1)))
        {
            S_i+=FindLastPosition(t, s.charAt(S_i+t.length-1)) +1;
        }
        else
            S_i+=t.length;
    }
    else
    {
        var l = 1;
        for (k = t.length-2; k>-1;k--) // last symb is correct, so see from t.l.-2
        {
            if (s.charAt(S_i + k)!=t.charAt(k))
            {
                if (sign[s.charAt(S_i + k)] == undefined )
                {
                    var delta = t.length - FindLastPosition(t, s.charAt(S_i + k)) - l;
                    if (delta>1)
                        S_i+=delta;
                    else
                        S_i+=1;
                    break;
                }
                else
                {
                    S_i+= t.length - l;
                    break;
                }
            }
            else
                l++;
        }
        if (l==t.length)
        {
            if(ans.length<10)
                ans.push(S_i);
            count++;
            S_i+=t.length;
        }
    }

}

WSH.echo("Count = " + count);
Show(ans);

function Check(sign)
{
    for (var i in sign)
        WSH.echo("'" + i + "'" + " = " + sign[i]);
}

function CheckIfContainsInT (sign, ch) // DON'T WORK!
{
    for (var j in sign)
    {
        if (j == ch)
            return true;
    }
    return false;
}

function FindLastPosition(str, ch)
{
    for(j = str.length-1; j>-1;j--)
    {
        if (str.charAt(j) == ch)
            return j;
    }
}

function Show(array)
{
    for (i = 0; i<array.length;i++)
    {
        WSH.echo(i + ": " + array[i]);
    }
}