How to get the index of an in a [duplicate]

Answer 1

OLD simple answer: $('ul#parent li:eq(1)').index()

NEW $('#li2').index()

Answer 2

var index = $("#li2").prevAll().length;  //assuming 0 based index

Answer 3

Use .index():

$('#li2').index();

IDs have to be unique so in case they are not in your HTML, you better fix this (e.g. by using classes).