Question

i have issues, how can I know for example contain <li> children <ul> or not?
thx all!

Answer 1

If you want to check if a <ul> element contains any <li> elements, you only need to use one selector –

var elements = $('ul#selector').find('li');
if (elements.length){
  // the <ul> has child <li> elements
}else{
  // no <li> elements found
}

This of course can be written in a single conditional statement –

var childElements =  $('ul#selector > li').length;