Searches every matched element for the object and returns the index of the element, if found, starting with zero. Returns -1 if the object wasn't found. Object to search for Returns the index for the element with ID foobar <div id="foobar"><b></b><span id="foo"></span></div> $("*").index( $('#foobar')[0] ) 0 Returns the index for the element with ID foo within another element <div id="foobar"><b></b><span id="foo"></span></div> $("*").index( $('#foo')[0] ) 2 Returns -1, as there is no element with ID bar <div id="foobar"><b></b><span id="foo"></span></div> $("*").index( $('#bar')[0] ) -1