There is a mistake here in that new Array(100).fill(null).map(() => new Array(100).fill(null)) is faster than Array.from({ length: 100 }, => Array.from({ length: 100 }, => null)); When testing arrays of all sizes (10 to 1000), Array.from is ~67% slower than new Array see: jsbench.me/z3l905yt6p/2

Mar 3, 2012 · Probably the best way to do multi-dimensional arrays is creating then on the fly using loops. so you can have like array[x][y][z] like I saw your 3D-array tag. To loop trough is not that hard, you can verify the length of the array, when you reach the end of one dimension e.g. z increase the y by one and reset z to 0. Exemple constructor of 2d ...

May 22, 2013 · Could somebody please help me to create an array of array.I have a matrix calculator and I want to create an array of arrays ('smaller').How can I do it?The functiions create2Darray and calculateDet are working ok,so now problem with them.Would be really grateful for the help.I need an array of these arrays (main matrix's minors) to calculate ...

May 4, 2012 · If we would use ES2015 we can use spread operator which will spread empty Array inside another Array, so we will get iterable Array : [...new Array(10)] // -> [undefined, undefined, undefined, ...] But if we don't use ES2015 and don't have polyfills, there is also a way to create dynamic Array without loop in ES5.

The preferred way of creating a array in javascript is var employess = []; not var employees=new Array(); – Mattias Jakobsson Commented Feb 12, 2010 at 10:08

I'm looking for any alternatives to the below for creating a JavaScript array containing 1 through to N where N is only known at runtime. var foo = []; for (var i = 1; i <= N; i++) { foo.push(i); } To me it feels like there should be a way of doing this without the loop.

Feb 15, 2017 · Creating array inside an array in javascript. Ask Question Asked 8 years, 2 months ago. Modified 8 years ...

Jan 31, 2011 · Defining JavaScript Arrays and Array Entries 1. JavaScript Array Entries. JavaScript pretty much has 2 types of array entries, namely mappable and unmappable. Both entry types are iterable, meaning they both work with the for-of loop. 2. JavaScript Arrays. A JavaScript array can contain both mappable and unmappable array entries.

Jul 20, 2018 · There's something else going on I don't understand. I'm creating a new array with new Array(2) and what I get back is [ <2 empty items> ] not [undefined, undefined]. Using .map on the former has no effect. However, I can iterate over it using a for...of loop. If I create a new array using literal notation a = [undefined, undefined] then I can ...

Not really, Array.from() here is basically creating an array, iterating through it with map(), calling a function on each item to create a new array, then discarding the first array... For a small arrays this may be innocuous, for larger arrays, this is the kind of pattern that result in people calling browsers "memory hogs" :) –