Lotto Picker

Many countries these days have some sort of lottery or lotto or pools (or whatever they call it) that requires you to select so many numbers out of a given total and if your numbers (or some of them) are drawn then you win a prize.

One problem in entering such a competition (apart from the extremely high odds against your numbers actually being the ones selected) is how you choose those numbers in the first place. If there are more than 28 numbers in the draw (which applies to just about all of them) then selecting significant dates will give you a selection skewed towards lower numbers. With most of these sorts of competition you get the best payout (assuming that you win) if as few as possible other people share the same numbers. Without being able to know what combinations have been selected by the least number of other people you have the best chance by selecting numbers at random.

So how do you pick your random numbers? Well a simple piece of Javascript can do it for you. Here is a Javascript function that will select a specified number of picks out of a larger selection of numbers starting from 1:

Simply pass in the number of picks you want made and how many numbers there are to pick from and the above function will return a comma separated list containing the number of picks that you asked for.

Want to see it in action? Well the following form grabs the number of picks and the total to pick them from out of the form, validates the values that you enter and then calls the above function to extract the required number of picks for you. If you don't like the first set of numners it chooses then just press the Go button again to get a new set of picks.

This Javascript function is a good example of how you can combine together several of the array methods to produce results like this involving very little code compared to the amount of code that would be required if fewer of the methods were used. Here we use push to add the numbers to the array to start with, sort (with the comparison function overridden) to sort into random order, slice to grab the desired number of results, and join to convert the results into a comma separated text string.