How to convert an array of key-value tuples into an object

Question

I have an array         cardType    iDEBIT          txnAmount    17 64          txnId    20181          txnType    Purchase          txnDate    2015 08 13 21 50 04          respCode    0          isoCode    0          authCode              acquirerInvoice    0          message              isComplete    true          isTimeout    false        But I can t access data via an array s key  e g  arr  txnId   does not return 20181  How can I convert the above array of tuples into an object  so that I can easily access data by key

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In my case  all other solutions didn t work  but this one did   obj       arr    my arr is in a form   name   the name   email   the email com

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ES5 Version using  reduce    const object   array reduce function accumulatingObject   key  value       accumulatingObject key    value    return accumulatingObject

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A more idiomatic approach would be to use Array prototype reduce    x000D   x000D  var arr     x000D       cardType    iDEBIT     x000D       txnAmount    17 64     x000D       txnId    20181     x000D       txnType    Purchase     x000D       txnDate    2015 08 13 21 50 04     x000D       respCode    0     x000D       isoCode    0     x000D       authCode         x000D       acquirerInvoice    0     x000D       message         x000D       isComplete    true     x000D       isTimeout    false    x000D     x000D   x000D  var obj   arr reduce function  o  currentArray    x000D    var key   currentArray 0   value   currentArray 1  x000D    o key    value x000D    return o x000D         x000D   x000D  console log obj  x000D  document write JSON stringify obj  split      join    lt br gt     x000D   x000D   x000D    This is more visually appealing  when done with ES6  rest parameters  syntax   let obj   arr reduce  o    key  value      gt        o key    value     return o

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When I used the reduce function with acc i    cur  it returned a kind of object that I needed to access it like a array using this way obj i  property  But using this way I have the Object that I wanted and I now can access it like obj property    function convertArraytoObject arr            var obj   arr reduce function  acc  cur  i                acc   cur              return acc                          return obj

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Use Map   new Map array        The Map object holds key-value pairs and remembers the original   insertion order of the keys  Any value  both objects and primitive   values  may be used as either a key or a value    This works because the type of your variable array is Array lt  key value  gt   The Map constructor can be initialized with an array of arrays where the first element of the inner arrays is the key and the second is the value    x000D   x000D  const array     x000D      cardType    iDEBIT    x000D      txnAmount    17 64    x000D      txnId    20181    x000D      txnType    Purchase    x000D      txnDate    2015 08 13 21 50 04    x000D      respCode    0    x000D      isoCode    0    x000D      authCode        x000D      acquirerInvoice    0    x000D      message        x000D      isComplete    true    x000D      isTimeout    false   x000D     x000D   x000D  const obj   new Map array   x000D   x000D  console log obj get  txnDate     x000D   x000D   x000D

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arr reduce  o   key  value     gt       o   key   value

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Update June 2020 ECMAScript 2021  brings Object fromEntries which does exactly the requirement   x000D   x000D  const array           cardType    iDEBIT              txnAmount    17 64              txnId    20181              txnType    Purchase              txnDate    2015 08 13 21 50 04              respCode    0              isoCode    0              authCode                  acquirerInvoice    0              message                  isComplete    true              isTimeout    false              const obj   Object fromEntries array   console log obj   x000D   x000D   x000D   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Object fromEntries This will do it   x000D   x000D  const array           cardType    iDEBIT              txnAmount    17 64              txnId    20181              txnType    Purchase              txnDate    2015 08 13 21 50 04              respCode    0              isoCode    0              authCode                  acquirerInvoice    0              message                  isComplete    true              isTimeout    false            var obj       array forEach function data       obj data 0     data 1      console log obj   x000D   x000D   x000D

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Short ES6 way with Airbnb code style  Exemple   const obj   arr reduce  prevObj   key  value     gt        prevObj   key   value

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use the following way to convert the array to an object easily   var obj       array forEach function e      obj e 0     e 1       This will use the first element as the key and the second element as the value for each element

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You could do this easily using array reduce in ES6  In this example we create a reducer function and pass an object      as initial value to the reduce function along with the reducer   x000D   x000D  const arr           cardType    iDEBIT     x000D       txnAmount    17 64     x000D       txnId    20181     x000D       txnType    Purchase     x000D       txnDate    2015 08 13 21 50 04     x000D       respCode    0     x000D       isoCode    0     x000D       authCode         x000D       acquirerInvoice    0     x000D       message         x000D       isComplete    true     x000D       isTimeout    false       x000D   x000D  const reducer    obj  item    gt    x000D    obj item 0     item 1   x000D    return obj  x000D     x000D   x000D  const result   arr reduce reducer       x000D   x000D  console log result   x000D   x000D   x000D

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With Object fromEntries  you can convert from Array to Object    x000D   x000D  var entries     x000D      cardType    iDEBIT    x000D      txnAmount    17 64    x000D      txnId    20181    x000D      txnType    Purchase    x000D      txnDate    2015 08 13 21 50 04    x000D      respCode    0    x000D      isoCode    0    x000D      authCode        x000D      acquirerInvoice    0    x000D      message        x000D      isComplete    true    x000D      isTimeout    false   x000D     x000D  var obj   Object fromEntries entries   x000D  console log obj   x000D   x000D   x000D

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easiest way to do it where array is of your JSON data     var obj       array forEach function Data   obj Data 0     Data 1

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I much more recommend you to use ES6 with it s perfect Object assign   method   Object assign        array map    key  value      gt      key   value         What happening here - Object assign   do nothing but take key value from donating object and puts pair in your result  In this case I m using     to split new array to multiply pairs  after map it looks like    cardType   iDEBIT            So in the end  new    receives every key property from each pair from mapped array

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The new JS API for this is Object fromEntries array of tuples   it works with raw arrays and or Maps

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Update 2020  As baao notes  Object fromEntries arr  now does this on all modern browsers   You can use Object assign  the spread operator  and destructuring assignment for an approach that uses map instead of  royhowie   s reduce  which may or may not be more intuitive  Object assign    arr map   key  val     gt     key   val      E g    x000D   x000D  var arr        cardType    iDEBIT          txnAmount    17 64          txnId    20181          txnType    Purchase          txnDate    2015 08 13 21 50 04          respCode    0          isoCode    0          authCode              acquirerInvoice    0          message              isComplete    true          isTimeout    false       var obj   Object assign    arr map   key  val     gt     key   val      console log obj  x000D   x000D   x000D

[javascript] How to convert an array of key-value tuples into an object

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