What is the difference between the two?
So I know that array.size()
is a function while array.length
is a property. Is there a usecase for using one over the other? Is one more efficient? (I would imagine .length
to be significantly faster as it is a property rather then a method call?) Why would one ever use the slower option? Are there some browsers that are incompatible with one or the other?
var x = [];
console.log(x.size());
console.log(x.length);
console.log(x.size()==x.length);
x =[1,2,3];
console.log(x.size());
console.log(x.length);
console.log(x.size()==x.length);
Will print:
0, 0, true
3, 3, true
This question is related to
javascript
arrays
The .size() method is deprecated as of jQuery 1.8. Use the .length property instead
The .size()
function is available in Jquery and many other libraries.
The .length
property works only when the index is an integer.
The length
property will work with this type of array:
var nums = new Array();
nums[0] = 1;
nums[1] = 2;
print(nums.length); // displays 2
The length
property won't work with this type of array:
var pbook = new Array();
pbook["David"] = 1;
pbook["Jennifer"] = 2;
print(pbook.length); // displays 0
So in your case you should be using the .length
property.
.size()
is not a native JS function of Array
(at least not in any browser that I know of).
.length
should be used.
.size()
does work on your page, make sure you do not have any extra libraries included like prototype that is mucking with the Array
prototype.
There might be some plugin on your browser that is mucking with the Array
prototype.
Actually, .size()
is not pure JavaScript method, there is a accessor property .size
of Set object that is a little looks like .size()
but it is not a function method, just as I said, it is an accessor property of a Set object to show the unique number of (unique) elements in a Set object.
The size accessor property returns the number of (unique) elements in a Set object.
const set1 = new Set();
const object1 = new Object();
set1.add(42);
set1.add('forty two');
set1.add('forty two');
set1.add(object1);
console.log(set1.size);
// expected output: 3
And length
is a property of an iterable object(array) that returns the number of elements in that array. The value is an unsigned, 32-bit integer that is always numerically greater than the highest index in the array.
const clothing = ['shoes', 'shirts', 'socks', 'sweaters'];
console.log(clothing.length);
// expected output: 4
array.length
isn't necessarily the number of items in the array:
var a = ['car1', 'car2', 'car3'];
a[100] = 'car100';
a.length; // 101
The length of the array is one more than the highest index.
As stated before Array.size()
is not a valid method.
Size detects duplicates, it will return the number of unique values
const set1 = new Set([1, 2, 3, 4, 5, 5, 5, 6]);
console.log(set1.size);
// expected output: 6
The property 'length' returns the (last_key + 1) for arrays with numeric keys:
var nums = new Array ();
nums [ 10 ] = 10 ;
nums [ 11 ] = 11 ;
log.info( nums.length );
will print 12!
This will work:
var nums = new Array ();
nums [ 10 ] = 10 ;
nums [ 11 ] = 11 ;
nums [ 12 ] = 12 ;
log.info( nums.length + ' / '+ Object.keys(nums).length );
.size()
is jQuery's, much probably you're either confusing with or took from someone else who had imported the jQuery library to his project.
If you'd have jQuery imported and you'd write like $(array).size()
, it would return the array length.
we can you use .length property to set or returns number of elements in an array. return value is a number
> set the length: let count = myArray.length;
> return lengthof an array : myArray.length
we can you .size in case we need to filter duplicate values and get the count of elements in a set.
const set = new set([1,1,2,1]); console.log(set.size) ;`
Source: Stackoverflow.com