How to remove element from array in forEach loop

Question

I am trying to remove an element in an array in a forEach loop  but am having trouble with the standard solutions I ve seen    This is what I m currently trying   review forEach function p      if p       u2022  u2022  u2022          console log  YippeeeE                         review splice p  1              I know it s getting into the if because I m seeing YippeeeeeE              in the console    MY PROBLEM  I know that my for loop and if logic are sound  but my attempt to remove the current element from the array is failing   UPDATE   Tried out Xotic750 s answer  and the element is still not being removed   Here is the function in my code   review forEach function  item  index  object        if  item       u2022  u2022  u2022            console log  YippeeeE                          object splice index  1             console log       item               Here is the output where the array is still not removed    Scott McNeil   reviewed 4 months ago    Mitsubishi is AMAZING     YippeeeE                                 So obviously it is going into the if statement as directed  but it s also obvious that the               is still there

User · Answer

You could also use indexOf instead to do this  var i   review indexOf   u2022  u2022  u2022    if  i     -1  review splice i 1

User · Answer

Here is how you should do it   review forEach function p index object      if review index        u2022  u2022  u2022          console log  YippeeeE                         review splice index  1

User · Answer

Use Array prototype filter instead of forEach   var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    b    c    b    a    e    review   review filter item   gt  item      a    log review

User · Answer

It looks like you are trying to do this  Iterate and mutate an array using Array prototype splice  x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    b    c    b    a     review forEach function item  index  object      if  item      a         object splice index  1            log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   Which works fine for simple case where you do not have 2 of the same values as adjacent array items  other wise you have this problem   x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    a    b    c    b    a    a     review forEach function item  index  object      if  item      a         object splice index  1            log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   So what can we do about this problem when iterating and mutating an array  Well the usual solution is to work in reverse  Using ES3 while but you could use for sugar if preferred  x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    a    b    c    b    a    a      index   review length - 1   while  index  gt   0      if  review index       a         review splice index  1          index -  1     log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   Ok  but you wanted to use ES5 iteration methods  Well and option would be to use Array prototype filter but this does not mutate the original array but creates a new one  so while you can get the correct answer it is not what you appear to have specified  We could also use ES5 Array prototype reduceRight  not for its reducing property by rather its iteration property  i e  iterate in reverse   x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    a    b    c    b    a    a     review reduceRight function acc  item  index  object      if  item      a         object splice index  1                log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   Or we could use ES5 Array protoype indexOf like so   x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    a    b    c    b    a    a      index   review indexOf  a     while  index     -1      review splice index  1     index   review indexOf  a       log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   But you specifically want to use ES5 Array prototype forEach  so what can we do  Well we need to use Array prototype slice to make a shallow copy of the array and Array prototype reverse so we can work in reverse to mutate the original array   x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        var review     a    a    b    c    b    a    a     review slice   reverse   forEach function item  index  object      if  item      a         review splice object length - 1 - index  1            log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   Finally ES6 offers us some further alternatives  where we do not need to make shallow copies and reverse them  Notably we can use Generators and Iterators  However support is fairly low at present   x000D   x000D  var pre   document getElementById  out     function log result      pre appendChild document createTextNode result     n        function  reverseKeys arr      var key   arr length - 1     while  key  gt   0        yield key      key -  1         var review     a    a    b    c    b    a    a     for  var index of reverseKeys review       if  review index       a         review splice index  1          log review   x000D   lt pre id  out  gt  lt  pre gt  x000D   x000D   x000D   Something to note in all of the above is that  if you were stripping NaN from the array then comparing with equals is not going to work because in Javascript NaN     NaN is false  But we are going to ignore that in the solutions as it it yet another unspecified edge case  So there we have it  a more complete answer with solutions that still have edge cases  The very first code example is still correct but as stated  it is not without issues

User · Answer

Although Xotic750 s answer provides several good points and possible solutions  sometimes simple is better   You know the array being iterated on is being mutated in the iteration itself  i e  removing an item    index changes   thus the simplest logic is to go backwards in an old fashioned for     la C language     x000D   x000D  let arr     a    a    b    c    b    a    a    x000D   x000D  for  let i   arr length - 1  i  gt   0  i--    x000D    if  arr i       a     x000D      arr splice i  1   x000D      x000D    x000D   x000D  document body append arr join     x000D   x000D   x000D    If you really think about it  a forEach is just syntactic sugar for a for loop    So if it s not helping you  just please stop breaking your head against it

User · Answer

I understood that you want to remove from the array using a condition and have another array that has items removed from the array  Is right   How about this    x000D   x000D  var review     a    b    c    ab    bc    x000D  var filtered       x000D  for var i 0  i  lt  review length     x000D    if review i  charAt 0      a     x000D      filtered push review splice i 1  0    x000D     else  x000D      i    x000D      x000D    x000D   x000D  console log  review   review   x000D  console log  filtered   filtered   x000D   x000D   x000D    Hope this help     By the way  I compared  for-loop  to  forEach    If remove in case a string contains  f   a result is different    x000D   x000D  var review     of    concat    copyWithin    entries    every    fill    filter    find    findIndex    flatMap    flatten    forEach    includes    indexOf    join    keys    lastIndexOf    map    pop    push    reduce    reduceRight    reverse    shift    slice    some    sort    splice    toLocaleString    toSource    toString    unshift    values    x000D  var filtered       x000D  for var i 0  i  lt  review length     x000D    if  review i  includes  f      x000D      filtered push review splice i 1  0    x000D     else   x000D      i    x000D      x000D    x000D  console log  review   review   x000D  console log  filtered   filtered   x000D      x000D     review     concat     copyWithin     entries     every     includes     join     keys     map     pop     push     reduce     reduceRight     reverse     slice     some     sort     splice     toLocaleString     toSource     toString     values    x000D      x000D   x000D  console log                                                              x000D  review     of    concat    copyWithin    entries    every    fill    filter    find    findIndex    flatMap    flatten    forEach    includes    indexOf    join    keys    lastIndexOf    map    pop    push    reduce    reduceRight    reverse    shift    slice    some    sort    splice    toLocaleString    toSource    toString    unshift    values    x000D  filtered       x000D   x000D  review forEach function item i  object    x000D    if  item includes  f      x000D      filtered push object splice i 1  0    x000D      x000D      x000D   x000D  console log  -----------------------------------------    x000D  console log  review   review   x000D  console log  filtered   filtered   x000D   x000D      x000D     review     concat     copyWithin     entries     every     filter     findIndex     flatten     includes     join     keys     map     pop     push     reduce     reduceRight     reverse     slice     some     sort     splice     toLocaleString     toSource     toString     values   x000D      x000D   x000D   x000D    And remove by each iteration  also a result is different    x000D   x000D  var review     of    concat    copyWithin    entries    every    fill    filter    find    findIndex    flatMap    flatten    forEach    includes    indexOf    join    keys    lastIndexOf    map    pop    push    reduce    reduceRight    reverse    shift    slice    some    sort    splice    toLocaleString    toSource    toString    unshift    values    x000D  var filtered       x000D  for var i 0  i  lt  review length     x000D    filtered push review splice i 1  0    x000D    x000D  console log  review   review   x000D  console log  filtered   filtered   x000D  console log                                                              x000D  review     of    concat    copyWithin    entries    every    fill    filter    find    findIndex    flatMap    flatten    forEach    includes    indexOf    join    keys    lastIndexOf    map    pop    push    reduce    reduceRight    reverse    shift    slice    some    sort    splice    toLocaleString    toSource    toString    unshift    values    x000D  filtered       x000D   x000D  review forEach function item i  object    x000D    filtered push object splice i 1  0    x000D      x000D   x000D  console log  -----------------------------------------    x000D  console log  review   review   x000D  console log  filtered   filtered   x000D   x000D   x000D

User · Answer

The following will give you all the elements which is not equal to your special characters     review   jQuery grep  review  function   value         return   value       u2022  u2022  u2022

[javascript] How to remove element from array in forEach loop?

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