are there dictionaries in javascript like python

Question

i need to make a dictionary in javascript like this  i dont remember the exact notation  but it was something like   states dictionary   CT  alex harry   AK  liza alex   TX  fred  harry               is there such a thing in javascript

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I realize this is an old question  but it pops up in Google when you search for  javascript dictionaries   so I d like to add to the above answers that in ECMAScript 6  the official Map object has been introduced  which is a dictionary implementation   var dict   new Map    dict set  foo    bar       returns  bar  dict get  foo      Unlike javascript s normal objects  it allows any object as a key   var foo       var bar       var dict   new Map    dict set foo   Foo    dict set bar   Bar       returns  Bar  dict get bar      returns  Foo  dict get foo      returns undefined  as        foo and        bar dict get

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An old question but I recently needed to do an AS3 JS port  and for the sake of speed I wrote a simple AS3-style Dictionary object for JS    http   jsfiddle net MickMalone1983 VEpFf 2   If you didn t know  the AS3 dictionary allows you to use any object as the key  as opposed to just strings  They come in very handy once you ve found a use for them   It s not as fast as a native object would be  but I ve not found any significant problems with it in that respect   API     Constructor var dict   new Dict overwrite Boolean      If overwrite  allows over-writing of duplicate keys    otherwise  will not add duplicate keys to dictionary   dict put key  value    Add a pair dict get key    Get value from key dict remove key    Remove pair by key dict clearAll value    Remove all pairs with this value dict iterate function key  value    Send all pairs as arguments to this function      console log key   is key for   value         dict get key    Get value from key

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There were no real associative arrays in Javascript until 2015  release of ECMAScript 6   Since then you can use the Map object as Robocat states  Look up the details in MDN  Example  let map   new Map    map set  key     value1    value2     let values   map get  key     Without support for ES6 you can try using objects  var x   new Object    x  quot Key quot      quot Value quot    However with objects it is not possible to use typical array properties or methods like array length  At least it is possible to access the  quot object-array quot  in a for-in-loop

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Use JavaScript objects  You can access their properties like keys in a dictionary  This is the foundation of JSON  The syntax is similar to Python dictionaries  See  JSON org

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Have created a simple dictionary in JS here   function JSdict         this Keys           this Values             Check if dictionary extensions aren t implemented yet     Returns value of a key if   JSdict prototype getVal        JSdict prototype getVal   function  key            if  key    null                return  Key cannot be null                     for  var i   0  i  lt  this Keys length  i                  if  this Keys i     key                    return this Values i                                   return  Key not found                 Check if dictionary extensions aren t implemented yet     Updates value of a key if   JSdict prototype update        JSdict prototype update   function  key  val            if  key    null    val    null                return  Key or Value cannot be null                        Verify dict integrity before each operation         if  keysLength    valsLength                return  Dictionary inconsistent  Keys length don t match values                      var keysLength   this Keys length          var valsLength   this Values length          var flag   false          for  var i   0  i  lt  keysLength  i                  if  this Keys i     key                    this Values i    val                  flag   true                  break                                  if   flag                return  Key does not exist                           Check if dictionary extensions aren t implemented yet     Adds a unique key value pair if   JSdict prototype add        JSdict prototype add   function  key  val               Allow only strings or numbers as keys         if  typeof  key      number     typeof  key      string                 if  key    null    val    null                    return  Key or Value cannot be null                             if  keysLength    valsLength                    return  Dictionary inconsistent  Keys length don t match values                              var keysLength   this Keys length              var valsLength   this Values length              for  var i   0  i  lt  keysLength  i                      if  this Keys i     key                        return  Duplicate keys not allowed                                                this Keys push key               this Values push val                     else               return  Only number or string can be key                          Check if dictionary extensions aren t implemented yet     Removes a key value pair if   JSdict prototype remove        JSdict prototype remove   function  key            if  key    null                return  Key cannot be null                     if  keysLength    valsLength                return  Dictionary inconsistent  Keys length don t match values                      var keysLength   this Keys length          var valsLength   this Values length          var flag   false          for  var i   0  i  lt  keysLength  i                  if  this Keys i     key                    this Keys shift key                   this Values shift this Values i                    flag   true                  break                                  if   flag                return  Key does not exist                       The above implementation can now be used to simulate a dictionary as   var dict   new JSdict     dict add 1   one    dict add 1   one more    Duplicate keys not allowed    dict getVal 1   one   dict update 1   onne    dict getVal 1   onne   dict remove 1   dict getVal 1   Key not found     This is just a basic simulation  It can be further optimized by implementing a better running time algorithm to work in atleast O nlogn  time complexity or even less  Like merge quick sort on arrays and then some B-search for lookups  I Didn t give a try or searched about mapping a hash function in JS   Also  Key and Value for the JSdict obj can be turned into private variables to be sneaky   Hope this helps   EDIT    After implementing the above  I personally used the JS objects as associative arrays that are available out-of-the-box   However  I would like to make a special mention about two methods that actually proved helpful to make it a convenient hashtable experience    Viz  dict hasOwnProperty key  and delete dict key   Read this post as a good resource on this implementation usage   Dynamically creating keys in JavaScript associative array  THanks

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This is an old post  but I thought I should provide an illustrated answer anyway   Use javascript s object notation  Like so   states dictionary          CT    alex   harry           AK    liza   alex           TX    fred    harry        And to access the values   states dictionary AK 0    which is liza   or you can use javascript literal object notation  whereby the keys not require to be in quotes   states dictionary         CT   alex   harry          AK   liza   alex          TX   fred    harry

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Firefox 13  provides an experimental implementation of the map object similar to the dict object in python  Specifications here   It s only avaible in firefox  but it looks better than using attributes of a new Object    Citation from the documentation          An Object has a prototype  so there are default keys in the map  However  this can be bypassed using map   Object create null     The keys of an Object are Strings  where they can be any value for a Map    You can get the size of a Map easily while you have to manually keep track of size for an Object

[javascript] are there dictionaries in javascript like python?

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