Array size vs Array length

Question

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

User · Answer

The  size   method is deprecated as of jQuery 1 8  Use the  length property instead  See  https   api jquery com size

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

we can you use  length property to set or returns number of elements in an array  return value is a number   gt  set the length  let count   myArray length   gt  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

User · Answer

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   More information

[javascript] Array.size() vs Array.length

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