What is the most efficient way to concatenate N arrays?

Tackling large arrays

For whopping data corpses... sorry, I meant large arrays, applying a loop to concatenate arrays spares you from the dreaded "Maximum call stack size exceeded" nightmare. Let's see this in action:

let combined = array1;
for (let i = 1; i < arrays.length; i++) {
  combined.push.apply(combined, arrays[i]); // push it real good!
}


By iterating and pushing each element, you optimize the operation and bypass potential stack size limitations of spread or concat().

Pick your battle strategy

The quickest gun in the west isn't always the fastest in the east. The spread operator and concat() are apt for small to medium arrays, while utilizing a loop or apply() strategy could potentially save your code's day for mega-sized arrays. To prove the quickest draw, tools like jsperf or Benchmark.js are your loyal deputies.

Harnessing ES6 magic

If you're wrestling with arrays in a modern environment flashing its ES6 badge, the arr.flat() method offers a nifty way to concatenate arrays like magic. How about that?

const combined = arrays.flat(); // Flat is the new "in".


Mind the environmental fences

When you want to play it nice with older versions, you gotta mind your manners. Different JavaScript environments, like browsers or Node.js versions, have their own thresholds for maximum call stack size and array handling optimizations. Make sure you tip your hat to these fences before going full speed.

Dealing with special cases and testing

Be prepared for unexpected duels. Large array concatenation or specific JavaScript environment issues may arise up and challenge your code. Developing a dedicated library for such cases could be your winning card.

The real winners: Efficiency and performance

The smoothest whiskey isn't always the best. Similarly, even if the spread syntax charms you with its readability, let performance and efficiency be your primary goals. Always giddy up for the method that rides the fastest in your operation plains.

Storing your bounty

Think of reducing memory use as storing your bounty somewhere safe instead of leaving it all to the bartender. When possible, store the concatenated result back in one of the input arrays. This can help you ride longer on the memory range.