iterate through a map in javascript

Question

I have a structure like this   var myMap         partnr1    modelA    modelB    modelC        partnr2    modelA    modelB    modelC        I am going to iterate through each of the elements  partnr  with their associatives  models    I am trying a double  each iteration in order to achieve this  but nothing happens     each myMap  function  i  val          each i  function  innerKey  innerValue             setTimeout function                      variant   fadeOut  slow   function                        this  text innerKey    -    innerValue  fadeIn  slow                                 i   6000                  The effect with fading in and out that I am trying to achieve is working fine when using a single value array  Object   but not when I need to have more than one value for each key like here   Any ideas of how to accomplish this iteration succesfully and are there other ways than using a map that would be better in this case    Any suggestions would be of interest

User · Answer

Don t use iterators to do this  Maintain your own loop by incrementing a counter in the callback  and recursively calling the operation on the next item     each myMap  function    arr        processArray arr  0        function processArray arr  i        if  i  gt   arr length  return       setTimeout function                  variant   fadeOut  slow   function                    this  text i    -    arr i   fadeIn  slow                    Handle next iteration             processArray arr    i                      6000         Though there s a logic error in your code  You re setting the same container to more than one different value at  roughly  the same time  Perhaps you mean for each one to update its own container

User · Answer

Functional Approach for ES6  If you want to take a more functional approach to iterating over the Map object  you can do something like this const myMap   new Map    myMap forEach  value  key    gt        console log value  key

User · Answer

The callback to   each   is passed the property name and the value  in that order  You re therefore trying to iterate over the property names in the inner call to   each    I think you want     each myMap  function  i  val        each val  function innerKey  innerValue                           In the inner loop  given an object like your map  the values are arrays  That s OK  but note that the  innerKey  values will all be numbers   edit  mdash  Now once that s straightened out  here s the next problem       setTimeout function                            i   6000     The first time through that loop   i  will be the string  partnr1    Thus  that multiplication attempt will result in a NaN   You can keep an external counter to keep track of the property count of the outer map   var pcount   1    each myMap  function i  val        each val  function innerKey  innerValue        setTimeout function                         pcount     6000

User · Answer

I d use standard javascript   for  var m in myMap       for  var i 0 i lt myMap m  length i             do something with myMap m  i                 Note the different ways of treating objects and arrays

User · Answer

An answer to your Question from 2019   It depends on what version of ECMAScript you use   Pre ES6   Use any of the answers below  e g    for  var m in myMap       for  var i 0 i lt myMap m  length i             do something with myMap m  i                 For ES6  ES 2015    You should use a Map object  which has the entries   function   var myMap   new Map    myMap set  0    foo    myMap set 1   bar    myMap set      baz     for  const  key  value  of myMap entries        console log key  value       For ES8  ES 2017    Object entries   was introduced   const object     a   1   b   2   c    3   for  const  key  value  of Object entries object       console log key  value

[javascript] iterate through a map in javascript

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