How to replace item in array

Question

Each item of this array is some number  var items   Array 523 3452 334 31     5346    How to replace some item with a new one  For example  we want to replace 3452 with 1010  how would we do this

User · Answer

The easiest way is to use some libraries like underscorejs and map method   var items   Array 523 3452 334 31    5346      map items  function num      return  num    3452    1010   num         gt   523  1010  334  31     5346

User · Answer

The Array indexOf   method will replace the first instance   To get every instance use Array map     a   a map function item    return item    3452   1010   item        Of course  that creates a new array   If you want to do it in place  use Array forEach     a forEach function item  i    if  item    3452  a i    1010

User · Answer

var items   Array 523 3452 334 31 5346     If you know the value then use   items items indexOf 334     1010    If you want to know that value is present or not  then use   var point   items indexOf 334    if  point     -1        items point    1010      If you know the place  position  then directly use   items --position    1010    If you want replace few elements  and you know only starting position only means   items splice 2  1  1010  1220     for more about  splice

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Here is the basic answer made into a reusable function   function arrayFindReplace array  findValue  replaceValue       while array indexOf findValue      -1           let index   array indexOf findValue           array index    replaceValue

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Use indexOf to find an element  var i   items indexOf 3452   items i    1010

User · Answer

First  rewrite your array like this    var items    523 3452 334 31    5346     Next  access the element in the array through its index number  The formula to determine the index number is  n-1  To replace the first item  n 1  in the array  write   items 0    Enter Your New Number    In your example  the number 3452 is in the second position  n 2   So the formula to determine the index number is 2-1   1  So write the following code to replace 3452 with 1010   items 1    1010

User · Answer

Easily accomplished with a for loop   for  var i   0  i  lt  items length  i        if  items i     3452          items i    1010

User · Answer

Answer from  gilly3 is great    How to extend this for array of objects  I prefer the following way to update the new updated record into my array of records when I get data from the server  It keeps the order intact and quite straight forward one liner    users   users map u   gt  u id     editedUser id   u   editedUser     x000D   x000D  var users     x000D   id  1  firstname   John   lastname   Sena    x000D   id  2  firstname   Serena   lastname   Wilham    x000D   id  3  firstname   William   lastname   Cook   x000D     x000D   x000D  var editedUser    id  2  firstname   Big Serena   lastname   William    x000D   x000D  users   users map u   gt  u id     editedUser id   u   editedUser   x000D   x000D  console log  users - gt     users   x000D   x000D   x000D

User · Answer

To replace the second element in the array arr    1  7  9   with the value 8 arr 1    8

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presentPrompt id productqty        let alert   this forgotCtrl create         title   Test         inputs                        name   pickqty             placeholder   pick quantity                                 name   state             value   verified             disabled true            placeholder   state                             buttons                        text   Ok             role   cancel             handler  data   gt                 console log  dataaaaname  data pickqty               console log  dataaaapwd  data state               for  var i   0  i  lt  this cottonLists length  i                  if  this cottonLists i  id    id                   this cottonLists i  real stock   data pickqty                                        for  var i   0  i  lt  this cottonLists length  i                  if  this cottonLists i  id    id                 this cottonLists i  state    verified                                           Log object to console again              console log  After update     this cottonLists              console log  Ok clicked                                                alert present         As per your requirement you can change fields and array names  thats all  Enjoy your coding

User · Answer

First method  Best way in just one line to replace or update item of array  array splice array indexOf valueToReplace   1  newValue    Eg    let items     JS    PHP    RUBY     let replacedItem   items splice items indexOf  RUBY    1   PYTHON    console log replacedItem      RUBY   console log items      JS    PHP    PYTHON     Second method  An other simple way to do the same operation is    items items indexOf oldValue     newValue

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The immutable way to replace the element in the list using ES6 spread operators and  slice method   const arr     fir    next    third    item    next   const nextArr          arr slice 0  arr indexOf item        second        arr slice arr indexOf item    1      Verify that works  console log arr            fir    next    third    console log nextArr       fir    second    third

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Well if anyone is interresting on how to replace an object from its index in an array  here s a solution   Find the index of the object by its id   const index   items map item   gt  item id  indexOf objectId    Replace the object using Object assign   method   Object assign items index   newValue

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You can edit any number of the list using indexes  for example     items 0    5  items 5    100

User · Answer

items items indexOf 3452     1010  great for simple swaps  try the snippet below  x000D   x000D  const items   Array 523  3452  334  31  5346   console log items   items items indexOf 3452     1010 console log items  x000D   x000D   x000D

User · Answer

var index   items indexOf 3452    if  index     -1        items index    1010      Also it is recommend you not use the constructor method to initialize your arrays  Instead  use the literal syntax   var items    523  3452  334  31  5346     You can also use the   operator if you are into terse JavaScript and want to shorten the -1 comparison   var index   items indexOf 3452    if   index        items index    1010      Sometimes I even like to write a contains function to abstract this check and make it easier to understand what s going on  What s awesome is this works on arrays and strings both   var contains   function  haystack  needle        return    haystack indexOf needle          can be used like so now  if  contains items  3452            do something else        Starting with ES6 ES2015 for strings  and proposed for ES2016 for arrays  you can more easily determine if a source contains another value   if  haystack includes needle            do your thing

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Here s a one liner  It assumes the item will be in the array    x000D   x000D  var items    523  3452  334  31  5346  x000D  var replace    arr  oldVal  newVal    gt   arr arr indexOf oldVal     newVal  arr  x000D  console log replace items  3452  1010   x000D   x000D   x000D

User · Answer

var index   Array indexOf Array value           if  index  gt  -1              Array splice index  1               from here you can delete a particular value from array and based on the same index   you can insert value in array     Array splice index  0  Array value

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If you want a simple sugar sintax oneliner you can just    elements   elements filter element   gt  element id     updatedElement id   push updatedElement     Like   let elements       id  1  name   element one       id  2  name   element two      const updatedElement     id  1  name   updated element one       If you don t have id you could stringify the element like    elements   elements filter element   gt  JSON stringify element      JSON stringify updatedElement    push updatedElement

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I solved this problem using for loops and iterating through the original array and adding the positions of the matching arreas to another array and then looping through that array and changing it in the original array then return it  I used and arrow function but a regular function would work too   var replace    arr  replaceThis  WithThis    gt        if   Array isArray arr   throw new RangeError  Error        var itemSpots           for  var i   0  i  lt  arr length  i              if  arr i     replaceThis  itemSpots push i              for  var i   0  i  lt  itemSpots length  i              arr itemSpots i     WithThis             return arr

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A functional approach to replacing an element of an array in javascript   x000D   x000D  const replace    array  index     items    gt      array slice 0  index      items     array slice index   1    x000D   x000D   x000D

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The easiest way is this   var items   Array 523 3452 334 31  5346   var replaceWhat   3452  replaceWith   1010  if     i   items indexOf replaceWhat     gt  0   items splice i  1  replaceWith    console log items    gt  gt  gt   5    523  1010  334  31  5346

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Replacement can be done in one line    x000D   x000D  var items   Array 523  3452  334  31  5346   x000D   x000D  items items map  e  i    gt   i  e   filter e   gt  e 1     3452  0  0     1010 x000D   x000D  console log items   x000D   x000D   x000D    Or create a function to reuse    x000D   x000D  Array prototype replace   function t  v    x000D      if  this indexOf t    -1  x000D          this this map  e  i    gt   i  e   filter e   gt  e 1     t  0  0     v  x000D       x000D   x000D    Check x000D  var items   Array 523  3452  334  31  5346   x000D  items replace 3452  1010   x000D  console log items   x000D   x000D   x000D

User · Answer

Here attached the code which replace all items in array var temp count 0  layers info array forEach element   gt         if element     element JSON parse element    change this line if you want other change method  here I changed string to object      layers info array temp count  element       temp count

User · Answer

ES6 way   const items   Array 523  3452  334  31     5346     We wanna replace 3452 with 1010  solution   const newItems   items map item   gt  item     3452   1010   item     Surely  the question is for many years ago and for now I just prefer to use immutable solution  definitely  it is awesome for ReactJS   For frequent usage I offer below function   const itemReplacer    array  oldItem  newItem    gt    array map item   gt  item     oldItem   newItem   item

User · Answer

If using a complex object  or even a simple one  and you can use es6  Array prototype findIndex is a good one  For the OP s array  they could do    const index   items findIndex x   gt  x     3452  items index    1010   For more complex objects  this really shines  For example    const index        items findIndex         x   gt  x jerseyNumber     9  amp  amp  x school      Ohio State         items index  lastName    Utah  items index  firstName    Johnny

User · Answer

My suggested solution would be   items splice 1  1  1010     The splice operation will remove 1 item  starting at position 1 in the array  i e  3452   and will replace it with the new item 1010

[javascript] How to replace item in array?

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