Remove last item from array

Question

I have the following array   var arr    1 0 2     I would like to remove the last element i e  2   I used arr slice -1   but it doesn t remove the value

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With Lodash you can use dropRight  if you don t care to know which elements were removed     dropRight  1  2  3        gt   1  2     dropRight  1  2  3   2        gt   1

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Another approach is to filter based on index   arr filter  element  index    gt  index  lt  arr length - 1     Note  filter   creates new array  doesn t change existing one

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If you want to remove n item from end of array in javascript  you can easily use   arr splice -n  n

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var arr    1 0 2   arr length--        removes the last element    need to check if arr length   0

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It s worth noting that slice will both return a new array  whereas  pop   and  splice   will mutate the existing array   If you like handling collections of data with a chained command style  you will really want to stick with slice for something like this   For example    x000D   x000D  myArray    1  2  3  4  5  6  7  8  9  10   x000D   x000D  var newArrayOfThings   myArray x000D     filter x   gt  x  gt  5                  only bigly things x000D     slice -1                           get rid of the last item x000D     map x   gt   The number is    x       map to a set of strings x000D   x000D   x000D    It can require a lot more messing about  and variable management  to do the same kind of thing with  pop   since unlike map  filter  etc  you don t get a new array back   It s the same kind of thing with push  which adds an item to the end of an array   You might be better off with concat since that lets you keep the flow going    x000D   x000D  myArray    1  2  3  4  5  6  7  8  9  10   x000D   x000D  var newArrayOfThings   myArray x000D     filter x   gt  x  gt  5                  only bigly things x000D     slice -1                           get rid of the  10  x000D     concat  100                        note with concat  you must pass an array x000D     map x   gt   The number is    x       map to a set of strings x000D     x000D   x000D   x000D

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2019 ECMA5 Solution   const new arr   arr reduce  d  i  idx  l    gt  idx  lt  l length - 1       d  i    d        Non destructive  generic  one-liner and only requires a copy  amp  paste at the end of your array

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You would need to do this since slice doesn t alter the original array    arr   arr slice -1     If you want to alter the original array you can use splice   arr splice -1  1     or pop   arr pop

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arr slice -1  will return a copy of the last element of the array  but leaves the original array unmodified   To remove the last n elements from an array  use arr splice -n   note the  p  in  splice     The return value will be a new array containing the removed elements   Simpler yet  for n    1  use val   arr pop

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This method is more helpful to delete and store the last element of an   array    var sampleArray    1 2 3 4     Declaring the array var lastElement   sampleArray pop     this command will remove the last element of  sampleArray  and stores in a variable called  lastElement  so that you can use it if required       Now the results are    console log sampleArray     This will give you  1 2 3  console log lastElement     this will give you 4

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say you have var arr    1 0 2   arr splice -1 1  will return to you array  1 0   while  arr slice -1 1  will return to you array  2

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I would consider  pop   to be the most  correct  solution  however  sometimes it might not work since you need to use array without the last element right there     In such a case you might want to use the following  it will return  1 2 3    x000D   x000D  var arr    1 2 3 4   x000D  console log arr splice 0 arr length-1    x000D   x000D   x000D    while  pop   would return 4    x000D   x000D  var arr    1 2 3 4   x000D  console log arr pop     x000D   x000D   x000D    which might not be desirable     Hope this saves you some time

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You can do this using  slice   method like   arr slice 0  -1         returns  1 0    Here is a demo    x000D   x000D  var arr    1  0  2   x000D  var newArr   arr slice 0  -1         returns  1 0  x000D   x000D  console log newArr   x000D      div1   text       arr         x000D      div2   text       newArr         x000D   lt script src  http   code jquery com jquery min js  gt  lt  script gt  x000D   lt b gt Original Array       lt  b gt  x000D   lt div id  div1  gt  lt  div gt  x000D   lt br  gt  x000D   lt b gt After slice 0  -1    lt  b gt  x000D   lt div id  div2  gt  lt  div gt  x000D   x000D   x000D    instead of doing    arr slice -1        returns  2    Here is a demo    x000D   x000D  var arr    1  0  2   x000D  var newArr   arr slice -1         returns  2  x000D   x000D  console log newArr   x000D      div1   text       arr         x000D      div2   text       newArr         x000D   lt script src  http   code jquery com jquery min js  gt  lt  script gt  x000D   lt b gt Original Array       lt  b gt  x000D   lt div id  div1  gt  lt  div gt  x000D   lt br  gt  x000D   lt b gt After slice -1    lt  b gt  x000D   lt div id  div2  gt  lt  div gt  x000D   x000D   x000D    Explanation -  Now the basic syntax of Array prototype slice   or in short slice   method is   arr slice  begin   end      Here    the begin parameter is zero-based index at which extraction from an array starts  So  lets say based on above example if we do something like  arr slice 0        returns  1 0 2    it would return all the array elements from start of sequence from position 0 and that is  1 0 2   Similarly  if we do  arr slice 1        returns  0 2    it would return  0 2  since 0 is at position 1 here and everything after that  Now  in your case you have passed a negative index i e   -1 as the begin parameter  which indicates an offset from the end of the sequence  So  slice -1  in your case extracts the last one array element in the sequence and that is 2  as we have already seen in the above demo    Now  let s talk about the end parameter in the slice   method syntax here  It is again a zero-based index at which extraction from an array ends  So  lets say we have a array like -  var arr    1  0  2  5  3  9     and we want to get just the 2 5 3 elements in the array  Now  position of 2 from start of the sequence is 2 and for last element 3 it is 4  We will need to end the extraction here a position 5  as we need to get the element before that position  So  we will simply implement slice   method here like  arr slice 2  5        returns  2 5 3    In your case  we have implemented -1 as the end parameter  so our code is like  arr slice 0  -1       returns  1 0    As a negative index  end indicates an offset from the end of the sequence  So  slice 0 -1  extracts the first element through the second-to-last element in the sequence  So  we get the desired output  We can also do like  arr slice 0  2        returns  1 0    we will get the same output  But  I have used -1 here as its easier to implement even for a long array like   0 2 3 1 2 9 3 6 3 9 1 0 2 9 0 1 1 2 3 4 7 9 1    If you just want to remove the last element  you don t want to sit  amp  calculate the position of last 9 here and the do like arr slice 0  22   You can then simply implement the negative index logic here  amp  do   arr slice 0  -1     same result as arr slice 0  22    Hope it helps

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splice index howmany  - This solution sounds good  But This howmany will work only for the positive array index  To remove last two items or three items use the index itself    For example  splice -2  to remove last two items  splice -3  for removing last three items

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This is good way to remove last item    if  arr    null  amp  amp  arr    undefined  amp  amp  arr length  gt  0          arr splice arr length - 1  1       Detail of splice as following   splice startIndex  number of splice

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Setup var myArray      quot John quot   23     quot cat quot   2        Only change code below this line var removedFromMyArray  removedFromMyArray   myArray pop

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Using the spread operator   x000D   x000D  const a    1 2 3  const       rest    a reverse    const withoutLast   rest reverse    console log withoutLast  x000D   x000D   x000D

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You could simply use  arr pop    This removes the last entry of the array   var arr    1 0 2    var popped   arr pop     Now arr    1 0   amp  popped   2

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There is a function for that  explanation here   arr pop

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learn by example   let array 1    1 2 3 4   let array 2    1 2 3 4   let array 3    1 2 3 4    array 1 splice -1 1      output -- gt   4       array 1    1 2 3  array 2 slice 0 -1       output -- gt   1 2 3   array 2    1 2 3 4  array 3 pop              output -- gt  4        array 3    1 2 3

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var a    1 2 3 4 5 6    console log a reverse   slice 1  reverse       Array 5    1  2  3  4  5

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Simply arr splice -1  will do

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Use splice startPosition  deleteCount  array splice -1 1

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Just use the following for your use case   var arr    1 2 3 4   arr pop     returns 4 as the value arr    value 4 is removed from the   arr   array variable   Just a note  When you execute pop   function even though the line returns the popped item the original array is effected and the popped element is removed

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Array prototype pop   by JavaScript convention   let fruit     apple    orange    banana    tomato    let popped   fruit pop     console log popped       tomato  console log fruit        apple    orange    banana

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var stack    1 2 3 4 5 6    stack reverse   shift     stack push 0     Output will be  Array 0 1 2 3 4 5   This will allow you to keep the same amount of array elements as you push a new value in

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You can do it in two way using splice        arr splice -1 1    arr splice arr length-1 1      splice position to start deleting  how many data to delete  takes two parameter     position to start deleting   The zero based index from where to start deleting   how many data to delete   From indicated index  how many consecutive data should be deleted     You can also remove the last element using pop   as pop   removes the last element from some array  Use arr pop

[javascript] Remove last item from array

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