I know that array is some kind of an object, but it also has numeric indexes. And arr.length is a property, which returns not the number of elements in the array, but the last index+1. We can remove the last element using decrement of length or function pop(). And the question is: What's the difference between these methods?

I know that array is some kind of an object, but it also has numeric indexes. And arr.length is a property, which returns not the number of elements in the array, but the last index+1. We can remove the last element using decrement of length or function pop(). And the question is: What's the difference between these methods?

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Share Improve this question Follow edited Aug 24, 2019 at 3:43 jpyams 4,40499 gold badges4343 silver badges7070 bronze badges asked Jul 6, 2019 at 16:56 RaptorDeveloperRaptorDeveloper 32522 silver badges1414 bronze badges 2

• you get the item with pop...? what is the changing of length for? – Nina Scholz Commented Jul 6, 2019 at 16:57
• 1 Is it an antipattern to set an array length in JavaScript? and Javascript array length modification implications – adiga Commented Jul 6, 2019 at 17:00

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2 Answers 2

Sorted by: Reset to default 8

Some differences:

• pop returns the value of the entry that you're removing, assigning to length doesn't.

• pop is a method call; assigning to length is an assignment operation.

• pop on an array whose length is 0 returns undefined and doesn't change the array. array.length -= 1 on an array with a length of 0 causes an error.

.pop() also returns the last element (which is often wanted):

const last = array.pop();
// vs
const last = array[array.length - 1];
array.length -= 1;

Now you can decide yourself which one of the above is more readable ...