I’m working with a two-dimensional array in JavaScript and running into trouble when trying to process its contents. My goal is to calculate the intersection between multiple arrays, but some of these arrays might be empty.
Here’s what I’m dealing with:
var dataFromServer = [[456], []];
var intersectionResult = _.intersection(dataFromServer[0]);
The problem is that when I access dataFromServer[0], I only get [456] instead of getting both [456] and [] which is what I actually need for the intersection function to work properly.
I’m using the underscore library for this operation. How can I extract all the sub-arrays from my main array so that the intersection method receives the complete set of arrays to compare? Any suggestions on how to approach this would be really helpful.
u nailed it! just remember that dataFromServer[0] only gets the first sub-array. use the spread operator like _.intersection(...dataFromServer) or apply method to pass all subarrays properly. ur code will work then!
You’re only passing one array to the intersection function instead of spreading all the sub-arrays as separate arguments.
Use the spread operator to unpack all arrays:
var dataFromServer = [[456], []];
var intersectionResult = _.intersection(...dataFromServer);
This spreads dataFromServer so intersection gets [456] and [] as separate parameters instead of just the first element.
Or use apply:
var intersectionResult = _.intersection.apply(null, dataFromServer);
Both will pass all your sub-arrays to the intersection function properly.
If you’re doing this kind of data processing regularly, consider automating the whole pipeline. I’ve dealt with similar scenarios where server data comes in various formats and needs processing.
Latenode makes this really clean - you can set up workflows that automatically handle array transformations, API calls, and data processing without writing repetitive JavaScript. Just drag and drop the logic and it handles all the array manipulation.
The problem is how intersection methods handle arguments. When you write _.intersection(dataFromServer[0]), you’re passing a single array [456] to the function. But intersection needs multiple arrays as separate parameters to compare them. I hit this exact same issue last year processing API filter data. You need all sub-arrays passed as individual arguments, not just one element. Use spread syntax ...dataFromServer to unpack your array so intersection gets [456], [] as two separate parameters. Quick heads up though - empty arrays in your intersection will always return empty results since there’s nothing common between a populated array and an empty one. Just make sure that’s what you want.