Question

Some folks helped me build a randomizer:

function makeid() {
    var text = "";
    var possibleChars = "._";
    var possibleLetters = "AB";

    text += possibleLetters.charAt(Math.floor(Math.random() * possibleLetters.length));
    for( var i=0; i < Math.floor(Math.random() * 3)+1; i++ )
        text += " " + possibleChars.charAt(Math.floor(Math.random() * possibleChars.length));

    return text;
}

for (var i=0; i < 20; i++)
    $("body").append("<div>" + makeid() + "</div>");

It outputs something like this:

B . .

B .

B _ _

A _ .

B .

A .

A _

B . .

A _

A _

B _ .

B . . .

B _

B _ .

I want to modify the JavaScript code above so that A and B don’t repeat themselves more than twice in a row:

A . .

B .

B _ _

A _ .

B .

A .

A _

B . .

A _

A _

B _ .

B . . .

A _

B _ .

Any suggestions?

Answer 1

Here you go – not pretty, but should work (alas, not tested):

function makeid() {
    var text = "";
    var possibleChars = "._";
    var possibleLetters = "AB";

    while ( true ) {
        var ch= possibleLetters.charAt(Math.floor(Math.random() * possibleLetters.length));
        if ( this._prev1 != this._prev2 || this._prev1 != ch ) break;
    }
    this._prev2= this._prev1;
    this._prev1= ch;
    text += ch;

    for( var i=0; i < Math.floor(Math.random() * 3)+1; i++ )
        text += " " + possibleChars.charAt(Math.floor(Math.random() * possibleChars.length));

    return text;
}