In JavaScript, you can use the "remainder" operator which uses a built-in modulo function in the JavaScript engine to give you the remainder of the division operation. The syntax is "var1 % var2", which will give you the remainder of var1 divided by var2.
So, to answer the posted question about lines that are multiples of 33, you would write:
for (var i = 0; i < lineCount; i++) {
if (i % 33 === 0) {
//this line is a multiple of 33, since the value stored in the variable "i", when divided by 33, gives us a remainder of 0
}
}
Modulus math can also be useful for things like finding odd or even rows, for the purpose of applying, say, a background color to every other row in an HTML table. NOTE: CSS3 allows for this to be handled directly with a CSS style, but that's another post.
Following the example of finding odd rows, you could code as follows:
for (var i = 0; i < data.length; i++) {
if (data[i] % 2 === 1) {
//odd row -> write out a tr with a background color
} else {
//even row -> write out a tr without a background color
}
}
Performing "% 2" is basically performing an odd/even test, telling you if the number being tested is a multiple of 2 or not.
The remainder operation can, of course, be performed using any number.
