如何在合并，排序javascript数组时提高性能

Question

I have two arrays. One is sorted, the other is not.

The sorted array is pretty big, let's say 90,000 entries. The second array will be short - currently no more than 401.

The problem is that I load a file, and read that file to determine values to put in to the short array, when I am done with that file the short array has to be merged with the sorted array and serialized to disk. I do the merge and sort as you would expect:

var hashes = [
"M2E0Mzk3YmItOWUzMC00ZmMwLWFhZDQtYTA0NTk0YWIwYjhjXw==mtg0mtq3nze2nw",
"M2ExZjNmNDktODdhOS00ODJiLTg2NzQtM2NiODQ1Njc1ZmYzXw==lte0mzg2otgxmdk",
"M2EzNTExM2UtY2JmYS00ZjAzLTgwZmMtMjg4ZDJkZjA5YzJjXw==mtcxmjqxmdc1mq",
"M2EzZjkzZDQtODUwYS00ZjlkLTg3ZmQtZjliNTFjZmYxNjVhXw==mjgzodu3nji3" ];

var append_to_hashes = [
"M2E2NGZjNWEtMzkwYy00YzE4LTkzM2EtNDVmNjE1MjE2ZDViXw==ltcxmzk1otawng",
"M2ExZjE2NGItNzUwZi00YTU4LWI3OGMtZDVkNDA2YWE2MzRmXw==ltq3odgznja2op",
"M2ExZjE2NGItNzUwZi00YTU4LWI3OGMtZDVkNDA2YWE2MzRmXw==ltq3odgznja2oa"];

if(append_to_hashes.length > 0){
   hashes = hashes.concat(append_to_hashes);
   hashes = hashes.sort();
}

But I'm wondering if there is a more performant way to concatenate and sort the arrays.

Answer 1

You can sort the smaller array and then insert each item in proper place:

var big = [...]; // Big sorted array
var small = [...];  // Small unsorted array

small.sort();

for(let i = 0; i < big.length && small.length > 0; i++) {
    if(big[i].localeCompare(small[0]) > 0) {
        big.splice(i, 0, small.shift());
    }
}