JavaScript and Ajax for the Web: Visual QuickStart Guide, Seventh Edition

Using Do/While Loops

Sometimes you’ll need to have a loop in your code that loops around a number of times, but there’s no way of knowing in advance how many times you’ll want to loop. That’s when you’ll want to use a do/while loop: you want to do something, while some value is true. Script 3.9 writes out each row of numbers as always, but this time it checks first to see if a number has been used already before putting it in a cell. If it has, the script generates a new random number and repeats the process until it finds one that’s unique. Figure 3.6 shows the working, finally valid Bingo card.

Script 3.9. This script prevents numbers in a given column from being used more than once.

window.onload = initAll; var usedNums = new Array(76); function ...