In C, you can do something like this:
#define NESTEDFOR(i,j,n) for(i=0; i<n; i++) for(j=0; j<n; j++)
So you can use NESTEDFOR(x,y,200) to save time, because it will be replaced with for(x=0; x<200; x++) for(y=0; y<200; y++)
I suppose there is no way to do this in JavaScript since it's an Interpreted language, but I'm not sure.
Is there any way to do it in JavaScript?
JavaScript doesn't support an exact equivalent, but you can define it as an iterator -- similar to iterator methods for Arrays:
function nestedFor(n, fn) {
for (var i = 0; i < n; i++) {
for (var j = 0; j < n; j++) {
if (false === fn(i, j)) {
return;
}
}
}
}
nestedFor(200, function (i, j) {
// etc.
// `return false` to stop looping
});
Also, one option for some argument validation:
function nestedFor(n, fn) {
if (typeof n !== 'number' || !isFinite(n)) {
throw new TypeError('Invalid argument: Expected a finite number.');
}
if (typeof fn !== 'function') {
throw new TypeError('Invalid argument: Expected a function.');
}
// etc.
}
fn is function before starting the loops.
n is a Number at least, and possibly that it's positive (or adjust to support decrementing) and isn't Infinity or NaN. But, was just trying to show the simplest form and keep it close to the snippets in the question.Technically, that isn't actually C either - it is the cpp macro language. You can configure your system to use the cpp processor on your Javascript but many here would consider that an act of great evil. I actually do that for all of my Javascript code.
