Is there a way that I can check if a data attribute exists

Question

Is there some way that I can run the following   var data       dataTable   data  timer    var diffs        for var i   0  i   1  lt  data length  i          diffs i    data i   1  - data i      alert diffs join           Only if there is an attribute called data-timer on the element with an id of  dataTable

User · Accepted Answer

if      dataTable   data  timer                NOTE this only returns true if the data attribute is not empty string or a  falsey  value e g  0 or false   If you want to check for the existence of the data attribute  even if empty  do this   if  typeof     dataTable   data  timer        undefined

User · Answer

var data       dataTable   data  timer    var diffs        if  data length  gt  0     for var i   0  i   1  lt  data length  i          diffs i    data i   1  - data i      alert diffs join

User · Answer

In the interest of providing a different answer from the ones above  you could check it with Object hasOwnProperty      like this    if      dataTable   data   hasOwnProperty  timer              the data-time property exists  now do you business             alternatively  if you have multiple data elements you want to iterate over you can variablize the  data   object and iterate over it like this    var objData       dataTable   data     for   data in objData          if  data     timer                      do the do              Not saying this solution is better than any of the other ones in here  but at least it s another approach

User · Answer

I ve found this works better with dynamically set data elements   if      myelement   data  myfield

User · Answer

This is the easiest solution in my opinion is to select all the element which has certain data attribute   var data       dataTable data-timer     var diffs        for var i   0  i   1  lt  data length  i          diffs i    data i   1  - data i      alert diffs join           Here is the screenshot of how it works

User · Answer

if  typeof     dataTable   data  timer        undefined            your code here

User · Answer

If you want to distinguish between empty values and missing values you can use jQuery to check like this    lt div id  element  data-foo  bar  data-empty    gt  lt  div gt    lt script gt   foo  in     element   data       true  empty  in     element   data       true  other  in     element   data       false  lt  script gt    So from the original question you d do this   if  timer  in     dataTable   data           code

User · Answer

You can check by css attribute selection with  if      dataTable   is   data-timer             data-timer attribute exists

User · Answer

And what about   if      dataTable data-timer    length  gt  0           logic here

User · Answer

You can create an extremely simple jQuery-plugin to query an element for this     fn hasData   function key      return  typeof   this  data key      undefined         Then you can simply use     dataTable   hasData  timer     Gotchas    Will return false only if the value does not exist  is undefined   if it s set to false null it hasData   will still return true  It s different from the built-in   hasData   which only checks if any data on the element is set

User · Answer

You can use jQuery s hasData method    http   api jquery com jQuery hasData      The primary advantage of jQuery hasData element  is that it does not create and associate a data object with the element if none currently exists  In contrast  jQuery data element  always returns a data object to the caller  creating one if no data object previously existed    This will only check for the existence of any data objects  or events  on your element  it won t be able to confirm if it specifically has a  timer  object

User · Answer

I needed a simple boolean to work with  Because it s undefined of not present  and not false  I use the    to convert to boolean   var hasTimer         dataTable   data  timer    if  hasTimer                      An alternative solution would be using filter   if      dataTable   filter   data-timer    length   0

User · Answer

Or combine with some vanilla JS  if      dataTable   get 0  hasAttribute  data-timer

User · Answer

Wrong answer - see EDIT at the end  Let me build on Alex s answer   To prevent the creation of a data object if it doesn t exists  I would better do     fn hasData   function key        var  this     this       return   hasData  this   amp  amp  typeof  this data key       undefined        Then  where  this has no data object created    hasData returns false and it will not execute  this data key    EDIT  function   hasData element  works only if the data was set using   data element  key  value   not element data key  value   Due to that  my answer is not correct

User · Answer

All the answers here use the jQuery library  But the vanilla javascript is very straightforward  If you want to run a script only if the element with an id of  dataTable also has a data-timer attribute  then the steps are as follows     Locate the element const myElement   document getElementById  dataTable        Run conditional code if  myElement dataset hasOwnProperty  timer              CODE HERE

[javascript] Is there a way that I can check if a data attribute exists?

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