javascript - Get id attribute from a node in nodelist -

i have got nodelist using document.getelementsbyclassname method in javascript. check if first node has children , if not return document.getelementbyid nodes id. unsure of how id node list.

 var columns = document.getelementsbyclassname('.col-md-4.column');  if (countchildren(columns[0].childnodes) == 0) {     return document.getelementbyid(columns[0].) //not sure goes here } 

if have dom node, has id property, can't use getelementbyid property

var columns = document.queryselectorall('.col-md-4.column');  if ( countchildren(columns[0].childnodes) == 0 ) {     return columns[0].id; } 

note getelementsbyclassname takes classes without period, better support might use queryselectorall