How to loop through array in jQuery

Question

I am trying to loop through an array  I have the following code    var currnt image list   21 32 234 223    var substr   currnt image list split          array here   Am trying to get all the data out of the array  Can some one lead me in the right path please

User · Answer

Use jQuery each    There are other ways but each is designed for this purpose       each substr  function index  value       alert value          And do not put the comma after the last number

User · Answer

jQuery each    jQuery each    jQuery each array  callback    array iteration  jQuery each array  function Integer index  Object value        object iteration  jQuery each object  function string propertyName  object propertyValue        example    x000D   x000D  var substr    1  2  3  4   x000D    each substr   function index  val     x000D    console log index  val  x000D      x000D   x000D  var myObj     firstName   skyfoot    x000D    each myObj  function propName  propVal    x000D    console log propName  propVal   x000D      x000D   lt script src  https   ajax googleapis com ajax libs jquery 2 1 1 jquery min js  gt  lt  script gt  x000D   x000D   x000D    javascript loops for array  for loop  for  initialExpression  condition  incrementExpression    statement   example   x000D   x000D  var substr    1  2  3  4   x000D   x000D    loop from 0 index to max index x000D  for var i   0  i  lt  substr length  i      x000D    console log  loop   substr i   x000D    x000D   x000D    reverse loop x000D  for var i   substr length-1  i  gt   0  i--    x000D    console log  reverse   substr i   x000D    x000D   x000D    step loop x000D  for var i   0  i  lt  substr length  i  2    x000D    console log  step   substr i   x000D    x000D   x000D   x000D    for in    dont really wnt to use this on arrays  use it on objects for var i in substr        console log substr i     note i returns index     for of  for var i of subs          can use break      console log i     note i returns value     forEach  substr forEach function v  i  a         cannot use break      console log v  i  a        Resources  MDN loops and iterators

User · Answer

Try this     grep array  function element

User · Answer

Use the each   function of jQuery   Here is an example     each currnt image list split       function index  value       alert index          value

User · Answer

for var key in substr            do something with substr key

User · Answer

Option 1   The traditional for-loop  The basics  A traditional for-loop has three components     the initialization   executed before the look block is executed the first time the condition   checks a condition every time before the loop block is executed  and quits the loop if false the afterthought   performed every time after the loop block is executed   These three components are seperated from each other by a   symbol  Content for each of these three components is optional  which means that the following is the most minimal for-loop possible    for               Do stuff     Of course  you will need to include an if condition     true    break     or an if condition     true    return    somewhere inside that for-loop to get it to stop running   Usually  though  the initialization is used to declare an index  the condition is used to compare that index with a minimum or maximum value  and the afterthought is used to increment the index    for  var i   0  length   10  i  lt  length  i          console log i         Using a tradtional for-loop to loop through an array  The traditional way to loop through an array  is this    for  var i   0  length   myArray length  i  lt  length  i          console log myArray i        Or  if you prefer to loop backwards  you do this    for  var i   myArray length - 1  i  gt  -1  i--        console log myArray i        There are  however  many variations possible  like eg  this one    for  var key   0  value   myArray key   var length   myArray length  key  lt  length  value   myArray   key         console log value           or this one      var i   0  length   myArray length  for    i  lt  length         console log myArray i        i            or this one    var key   0  value  for    value   myArray key            console log value       Whichever works best is largely a matter of both personal taste and the specific use case you re implementing   Note    Each of these variations is supported by all browsers  including v  ry old ones     Option 2   The while-loop  One alternative to a for-loop is a while-loop  To loop through an array  you could do this    var key   0  while value   myArray key          console log value       Note    Like traditional for-loops  while-loops are supported by even the oldest of browsers   Also  every while loop can be rewritten as a for-loop  For example  the while-loop hereabove behaves the exact same way as this for-loop    for var key   0 value   myArray key           console log value         Option 3   for   in and for   of  In JavaScript  you can also do this    for  i in myArray        console log myArray i        This should be used with care  however  as it doesn t behave the same as a traditonal for-loop in all cases  and there are potential side-effects that need to be considered  See Why is using  quot for   in quot  with array iteration a bad idea  for more details   As an alternative to for   in  there s now also for for   of  The following example shows the difference between a for   of loop and a for   in loop    var myArray    3  5  7   myArray foo    hello    for  var i in myArray      console log i      logs 0  1  2   foo     for  var i of myArray      console log i      logs 3  5  7     Note    You also need to consider that no version of Internet Explorer supports for   of  Edge 12  does  and that for   in requires at least IE10     Option 4   Array prototype forEach    An alternative to For-loops is Array prototype forEach    which uses the following syntax    myArray forEach function value  key  myArray        console log value         Note    Array prototype forEach   is supported by all modern browsers  as well as IE9      Option 5   jQuery each    Additionally to the four other options mentioned  jQuery also had its own foreach variation   It uses the following syntax      each myArray  function key  value        console log value

User · Answer

You can use a for   loop   var things   currnt image list split        for var i   0  i  lt  things length  i            Do things with things i

User · Answer

Alternative ways of iteration through array string with side effects   x000D   x000D  var str    21 32 234 223   x000D  var substr   str split       x000D   x000D  substr reduce  a x   gt  console log  reduce  x   0            return undefined x000D   x000D  substr every x  gt    console log  every  x   return true      return true x000D   x000D  substr some x  gt    console log  some  x   return false       return false x000D   x000D  substr map x  gt  console log  map  x                          return array x000D    x000D  str replace    d   g  x  gt  console log  replace  x           return string x000D   x000D   x000D

User · Answer

ES6 syntax with arrow function and interpolation     var data   a   b   c      data  each  index  element    gt            console log  current index     index  element     element

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Update  My other answer here lays out the non-jQuery options much more thoroughly  The third option below  jQuery each  isn t in it though      Four options   Generic loop   var i  for  i   0  i  lt  substr length    i           do something with  substr i       or in ES2015    for  let i   0  i  lt  substr length    i           do something with  substr i       Advantages  Straight-forward  no dependency on jQuery  easy to understand  no issues with preserving the meaning of this within the body of the loop  no unnecessary overhead of function calls  e g   in theory faster  though in fact you d have to have so many elements that the odds are you d have other problems  details    ES5 s forEach   As of ECMAScript5  arrays have a forEach function on them which makes it easy to loop through the array   substr forEach function item           do something with  item        Link to docs   Note  There are lots of other functions  not just forEach  see the answer referenced above for details    Advantages  Declarative  can use a prebuilt function for the iterator if you have one handy  if your loop body is complex the scoping of a function call is sometimes useful  no need for an i variable in your containing scope   Disadvantages  If you re using this in the containing code and you want to use this within your forEach callback  you have to either A  Stick it in a variable so you can use it within the function  B  Pass it as a second argument to forEach so forEach sets it as this during the callback  or C  Use an ES2015  arrow function  which closes over this  If you don t do one of those things  in the callback this will be undefined  in strict mode  or the global object  window  in loose mode  There used to be a second disadvantage that forEach wasn t universally supported  but here in 2018  the only browser you re going to run into that doesn t have forEach is IE8  and it can t be properly polyfilled there  either    ES2015  s for-of   for  const s of substr       Or  let  if you want to modify it in the loop body        do something with  s      See the answer linked at the top of this answer for details on how that works   Advantages  Simple  straightforward  offers a contained-scope variable  or constant  in the above  for the entry from the array   Disadvantages  Not supported in any version of IE   jQuery each   jQuery each substr  function index  item           do something with  item   or  this  is also  item  if you like         Link to docs   Advantages  All of the same advantages as forEach  plus you know it s there since you re using jQuery   Disadvantages  If you re using this in the containing code  you have to stick it in a variable so you can use it within the function  since this means something else within the function   You can avoid the this thing though  by either using   proxy   jQuery each substr    proxy function index  item           do something with  item    this  is the same as it was outside     this         or Function bind   jQuery each substr  function index  item           do something with  item    this  is the same as it was outside    bind this         or in ES2015   ES6    an arrow function   jQuery each substr   index  item    gt           do something with  item    this  is the same as it was outside        What NOT to do   Don t use for  in for this  or if you do  do it with proper safeguards   You ll see people saying to  in fact  briefly there was an answer here saying that   but for  in does not do what many people think it does  it does something even more useful    Specifically  for  in loops through the enumerable property names of an object  not the indexes of an array   Since arrays are objects  and their only enumerable properties by default are the indexes  it mostly seems to sort of work in a bland deployment  But it s not a safe assumption that you can just use it for that  Here s an exploration  http   jsbin com exohi 3  I should soften the  don t  above  If you re dealing with sparse arrays  e g   the array has 15 elements in total but their indexes are strewn across the range 0 to 150 000 for some reason  and so the length is 150 001   and if you use appropriate safeguards like hasOwnProperty and checking the property name is really numeric  see link above   for  in can be a perfectly reasonable way to avoid lots of unnecessary loops  since only the populated indexes will be enumerated

User · Answer

No need for jquery here  just a for loop works   var substr   currnt image list split       for var i 0  i lt  substr length  i        alert substr i

[javascript] How to loop through array in jQuery?

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