Array.size() vs Array.length
JavascriptArraysJavascript Problem Overview
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
Javascript Solutions
Solution 1 - Javascript
Array.size() is not a valid method
Always use the length property
There is a library or script adding the size method to the array prototype since this is not a native array method. This is commonly done to add support for a custom getter. An example of using this would be when you want to get the size in memory of an array (which is the only thing I can think of that would be useful for this name).
Underscore.js unfortunately defines a size
method which actually returns the length of an object or array. Since unfortunately the length property of a function is defined as the number of named arguments the function declares they had to use an alternative and size was chosen (count would have been a better choice).
Solution 2 - Javascript
.size()
is not a native JS function of Array
(at least not in any browser that I know of).
.length
should be used.
If
.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.
or
There might be some plugin on your browser that is mucking with the Array
prototype.
Solution 3 - Javascript
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.
Solution 4 - Javascript
.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.
Solution 5 - Javascript
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.
Solution 6 - Javascript
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 );
Solution 7 - Javascript
The .size() method is deprecated as of jQuery 1.8. Use the .length property instead
Solution 8 - Javascript
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
Solution 9 - Javascript
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
Solution 10 - Javascript
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) ;`