Question

Does Not Work

CSS

.active 
{
    display: block;
}

JS

$("#li_1 ul").addClass('active');

Does Work

JS

$("#li_1 ul").css('display', 'block');

Which leads to me my question, why does the css function work and not the addClass? There’s no difference between the selectors at all.

Additional info –

• Using jQuery version 1.6.4
• JS in question here resides in a .js file being included in an
  ASP.NET masterpage
• masterpage has link to stylesheet containing the CSS in question
  here (ie – the ‘active’ style is available to the masterpage)

Answer 1

What about using this statement:

.active {
  display:block !important;
}

I think something overrides your .active rule in your CSS stylesheet.

More informations about CSS priorities right here.