I'm having trouble grasping the concept of an array filled with empty values like this:
let arr=[,,,];
When I attempt to log the length, it shows 3 instead of 4.
let arr=[,,,];
console.log('length',arr.length);
console.log('arr[1]',arr[1]);I'm having trouble grasping the concept of an array filled with empty values like this:
let arr=[,,,];
When I attempt to log the length, it shows 3 instead of 4.
let arr=[,,,];
console.log('length',arr.length);
console.log('arr[1]',arr[1]);Did you know that trailing commas are actually optional in array literals, at least in modern JS? For example, when you have:
[<a valid list of items>,]this is the same as:
[<a valid list of items>]Therefore, an array like this:
[,,,]is essentially equivalent to:
[undefined, undefined, undefined,]The official specification refers to this construction as [ ElementList , Elision(opt) ].
Just remember, if you leave out an element at the end of an array with a trailing comma, it won't count towards the length of the Array.
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