Javascript foreach loop on associative array object

Question

Why my for for-each loop is not iterating over my JavaScript associative array object      defining an array var array           assigning values to corresponding keys array  Main      Main page   array  Guide      Guide page   array  Articles      Articles page   array  Forum      Forum board       expected  loop over every item     yet it logs only  last  assigned value -  Forum  for  var i   0  i  lt  array length  i          console log array i        EDIT  jQuery each   could be helpful  https   api jquery com jQuery each

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This is very simple approach  The Advantage is you can get keys as well   for  var key in array        var value   array key       console log key  value       For ES6   array forEach value   gt      console log value         For ES6   If you want value  index and the array itself   array forEach  value  index  self    gt      console log value  index  self

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arr jq TabContents key  sees the array as an 0-index form

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x000D   x000D  var obj     x000D    no    no   32   x000D    nt    no   32   x000D    nf    no   32  90  x000D     x000D   x000D  count   -1     which must be static value x000D  for  i in obj    x000D    count    x000D    if  obj hasOwnProperty i     x000D      console log obj i  count   x000D       x000D     x000D   x000D   x000D    in this code i used brackets method for call values in array because it contained array   however briefly the idea which a variable i has a key of property and with a loop called both values of associate array  perfect Method   if you interested  press like

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You can Do this  var array           assigning values to corresponding keys array 0     Main page   array 1     Guide page   array 2     Articles page   array 3     Forum board     array forEach value   gt        console log value

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There are some straightforward examples already  but I notice from how you ve worded your question that you probably come from a PHP background  and you re expecting JavaScript to work the same way -- it does not  A PHP array is very different from a JavaScript Array   In PHP  an associative array can do most of what a numerically-indexed array can  the array   functions work  you can count   it  etc   You simply create an array and start assigning to string-indexes instead of numeric   In JavaScript  everything is an object  except for primitives  string  numeric  boolean   and arrays are a certain implementation that lets you have numeric indexes  Anything pushed to an array will effect its length  and can be iterated over using Array methods  map  forEach  reduce  filter  find  etc   However  because everything is an object  you re always free to simply assign properties  because that s something you do to any object  Square-bracket notation is simply another way to access a property  so in your case   array  Main      Main Page     is actually equivalent to   array Main    Main Page     From your description  my guess is that you want an  associative array   but for JavaScript  this is a simple case of using an object as a hashmap  Also  I know it s an example  but avoid non-meaningful names that only describe the variable type  e g  array   and name based on what it should contain  e g  pages   Simple objects don t have many good direct ways to iterate  so often we ll turn then into arrays first using Object methods  Object keys in this case -- there s also entries and values being added to some browsers right now  which we can loop      assigning values to corresponding keys const pages       Main   Main page     Guide   Guide page     Articles   Articles page     Forum   Forum board       Object keys pages  forEach  page    gt  console log page

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The  length property only tracks properties with numeric indexes  keys    You re using strings for keys   You can do this   var arr jq TabContents          no need for an array  arr jq TabContents  Main     jq TabContents Main  arr jq TabContents  Guide     jq TabContents Guide  arr jq TabContents  Articles     jq TabContents Articles  arr jq TabContents  Forum     jq TabContents Forum   for  var key in arr jq TabContents        console log arr jq TabContents key        To be safe  it s a good idea in loops like that to make sure that none of the properties are unexpected results of inheritance   for  var key in arr jq TabContents      if  arr jq TabContents hasOwnProperty key       console log arr jq TabContents key        edit  mdash  it s probably a good idea now to note that the Object keys   function is available on modern browsers and in Node etc  That function returns the  own  keys of an object  as an array   Object keys arr jq TabContents  forEach function key  index      console log this key       arr jq TabContents     The callback function passed to  forEach   is called with each key and the key s index in the array returned by Object keys    It s also passed the array through which the function is iterating  but that array is not really useful to us  we need the original object   That can be accessed directly by name  but  in my opinion  it s a little nicer to pass it explicitly  which is done by passing a second argument to  forEach    mdash  the original object  mdash  which will be bound as this inside the callback   Just saw that this was noted in a comment below

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This is  essentially  incorrect in most cases   var array       array  Main      Main page     That creates a non-element property on the array with the name Main  Although arrays are objects  normally you don t want to create non-element properties on them   If you want to index into array by those names  typically you d use a Map or a plain object  not an array   With a Map  ES2015    which I ll call map because I m creative   let map   new Map    map set  Main    Main page      you then iterate it using the iterators from its values  keys  or entries methods  for instance   for  const value of map values             Here   value  will be   Main page    etc      Using a plain object  which I ll creatively call obj   let obj   Object create null      Creates an object with no prototype obj Main    Main page      Or   obj  Main      Main page      you d then iterate its contents using Object keys  Object values  or Object entries  for instance   for  const value of Object values proches X            Here   value  will be   Main page    etc

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Here is a simple way to use an associative array as a generic Object type    x000D   x000D  Object prototype forEach   function cb   x000D     if this instanceof Array  return this forEach cb   x000D     let self   this  x000D     Object getOwnPropertyNames this  forEach  x000D         k   gt   cb call self  self k   k     x000D        x000D     x000D   x000D  Object  a 1 b 2 c 3   forEach  value  key   gt    x000D      console log  key value pair    key    value     x000D      x000D   x000D   x000D

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If the node js or browser supported Object entries    it can be used as an alternative to using Object keys    https   stackoverflow com a 18804596 225291      x000D   x000D  const h     x000D    a  1  x000D    b  2 x000D     x000D   x000D  Object entries h  forEach   key  value     gt  console log value    x000D     logs 1  2 x000D   x000D   x000D    in this example  forEach uses Destructuring assignment of an array

[javascript] Javascript foreach loop on associative array object

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