Select elements by attribute

Question

I have a collection of checkboxes with generated ids and some of them have an extra attribute  Is it possible to use JQuery to check if an element has a specific attribute  For example  can I verify if the following element has the attribute  myattr   The value of the attribute can vary    lt input type  checkbox  id  A  myattr  val attr  gt A lt  input gt    For example how can I get a collection of all checkboxes that have this attribute without checking one by one  Is this possible

User · Answer

In JavaScript      null    undefined      returns true   It s the difference between    and      Also  the name undefined can be defined  it s not a keyword like null is  so you re better off checking some other way  The most reliable way is probably to compare the return value of the typeof operator   typeof o     undefined    Nevertheless  comparing to null should work in this case     Assuming undefined is in fact undefined

User · Answer

This will work       A   0  hasAttribute  myattr

User · Answer

input attr    length might be a better option

User · Answer

simply      input name   value       more info  official docs

User · Answer

if      A   attr  myattr             attribute exists   else          attribute does not exist     EDIT   The above will fall into the else-branch when myattr exists but is an empty string or  0   If that s a problem you should explicitly test on undefined   if      A   attr  myattr       undefined           attribute exists   else          attribute does not exist

User · Answer

To select elements having a certain attribute  see the answers above   To determine if a given jQuery element has a specific attribute I m using a small plugin that returns true if the first element in  ajQuery collection has this attribute       hasAttr     helper plugin returning boolean if the first element of the collection has a certain attribute        fn hasAttr   function attr       return 0  lt  this length         amp  amp   undefined      typeof attr         amp  amp  undefined     attr         amp  amp  this 0  hasAttribute attr

User · Answer

In addition to selecting all elements with an attribute     someAttribute    or    input someAttribute    you can also use a function for doing boolean checks on an object such as in a click handler   if   this hasAttribute  myattr

User · Answer

A couple ideas were tossed around using  typeof   jQuery   is  and   filter  so I thought I would post up a quick perf compare of them  The typeof appears to be the best choice for this  While the others will work  there appears to be a clear performance difference when invoking the jq library for this effort

User · Answer

as in this post  using  is and the attribute selector     you can easily add a function  or prototype    function hasAttr  sel attr        return  sel is     attr

User · Answer

input A   attr  myattr      null

User · Answer

I have created npm package with intended behaviour as described above in question   Link to  npm  and  github   Usage is very simple  For example    lt p id  test  class  test  gt something lt  p gt      test   hasAttr  class     returns true   Works with camelcase too

User · Answer

I know it s been a long time since the question was asked  but I found the check to be clearer like this    if      A   is   myattr              attribute exists   else          attribute does not exist      As found on this site here   Documentation about is can be found here

User · Answer

Do you mean can you select them  If so  then yes       checkbox myattr

User · Answer

JQuery will return the attribute as a string   Therefore you can check the length of that string to determine if is set   if     input A   attr  myattr   length    0   return null  else  return    input A   attr  myattr

User · Answer

if       element   attr  my attr         return false     attribute doesn t exists

[jquery] Select elements by attribute

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