Cutting a string at nth occurrence of a character

Question

What I want to do is take a string such as this.those.that and get a substring to or from the nth occurrence of a character. So, from the start of the string to

Answer 1

I'm perplexed as to why you want to do things purely with string functions, but I guess you could do something like the following:

//str       - the string
//c         - the character or string to search for
//n         - which occurrence
//fromStart - if true, go from beginning to the occurrence; else go from the occurrence to the end of the string
var cut = function (str, c, n, fromStart) {
    var strCopy = str.slice(); //make a copy of the string
    var index;
    while (n > 1) {
        index = strCopy.indexOf(c)
        strCopy = strCopy.substring(0, index)
        n--;
    }

    if (fromStart) {
        return str.substring(0, index);
    } else {
        return str.substring(index+1, str.length);
    }
}

However, I'd strongly advocate for something like alex's much simpler code.