jquery selector for class within id

Question

Below  how should I select the elements that contain the class my class within the element with id    my id     Note that the element may also have another class  which I am not selecting for    lt div id    my id  gt       lt span class    my class hidden  gt hi lt  span gt       lt span class    my class  gt hello lt  span gt   lt  div gt    was trying      my id  class  my class

User · Accepted Answer

You can use the class selector along with descendant selector      my id  my class

User · Answer

Just use the plain ol  class selector      my id  my class    It doesn t matter if the element also has other classes  It has the  my class class  and it s somewhere inside  my id  so it will match that selector  Regarding performance According to the jQuery selector performance documentation  it s faster to use the two selectors separately  like this      my id   find   my class    Here s the relevant part of the documentation   ID-Based Selectors    Fast      quot  container div robotarm quot         Super-fast      quot  container quot    find   quot div robotarm quot      The  find   approach is faster because the first selection is handled without going through the Sizzle selector engine     ID-only selections are handled using document getElementById    which is extremely fast because it is native to the browser   Selecting by ID or by class alone  among other things  invokes browser-supplied functions like document getElementById   which are quite rapid  whereas using a descendent selector invokes the Sizzle engine as mentioned which  although fast  is slower than the suggested alternative

User · Answer

Also      container    find   div robotarm     is equal to      div robotarm     container

User · Answer

Always use     Super Fast     my id   find   my class       instead of      Fast      my id  my class      Have look at JQuery Performance Rules   Also at Jquery Doc

User · Answer

You can use find         my id   find  my class     Or maybe      my id   find  span     Both methods will word for what you want

User · Answer

I think your asking to select only  lt span class    my class  gt hello lt  span gt  this element   You have do like this  If I am understand your question correctly this is the answer       my id  class  my class     addClass  test      DEMO

[jquery] jquery, selector for class within id

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