JavaScript Tip: Working with Sparse Arrays

In this tutorial we cover how to deal with sparse arrays, or values of undefined and null inside an array. These concepts can be helpful when working with arrays.

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Tutorials referred to in this video:

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[aleksandregorov]

Thanks for another great video!
Just an observation here, we can filter out all null, undefined and 'empty' values with one filter method like this:
<pre>
let arr = [1, undefined, null, , 2, 3];
let filt = arr.filter(val => {
return val;
});
console.log(filt); // [1, 2, 3]
</pre>
It works cause undefined and null are falsy values and filter method ignores 'empty's.

[Alexandru-OM]

Thank you for the great videos, about the for in loop.. isn't that for looping over objects and for of loop for arrays? (I know in js arrays are objecta but still I wonder if its right :) )

[codelivewithme]

but why length -1 it will skip last element of array