Javascript - Insert array into another array with splice not working as expected

Question

I am trying to create a Cache Hashtable in Javascript.

by executing cache.splice(0,0, ...dataPage); I insert my data form the first till the dataPage.length position.

Let's say my dataPage size is always 10

My cache array should look like [0: {..}, 1: {..} ..... 9: {...}]

After that let's say I want to load the 5th page of data. I'm executing cache.splice(40,0, ...data);

I'm expecting my array to look like [[0: {..}, 1: {..} ..... 9: {...}, 40: {...}, 41:{...} ... 49{...}]

But it looks like [[0: {..}, 1: {..} ..... 9: {...}, 10: {...}, 11:{...} ... 12{...}]

Any idea how I can achieve my expected result??

Alexander Riedel · Accepted Answer · 2020-04-23 10:02:48Z

1

cache.splice(40,0, ...data) means, that you ...data will be inserted in at the 40th position of your cache.

If your cache doesn't have 40 elements, it cannot be inserted at that position.

Maybe you should first define a cache with the desired amount of positions and then splice your data into it.

EDIT sure you can do it dynamically. Something like this (I didn't test it, but maybe you get the point):

var cache= [];
var insertion_pos = 40;
var dataPage = [0: {..}, 1: {..} ..... 9: {...}, 10: {...}, 11:{...} ... 12:{...}]

for(var i=0; i < insertion_pos; i++) {
   cache.push(i);
}

cache.splice(insertion_pos, 0, ...dataPage)

edited Apr 23, 2020 at 10:02

answered Apr 23, 2020 at 9:46

Alexander Riedel

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1 Comment

Alexandros Rasidakis Over a year ago

So isn't there a way to expand my array dynamically in every insertion if needed?

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