javascript - Proper way to select child nodes in D3 -

i have created svg element nodes:

gnodes = svg.selectall("g.node")     .data(_nodes);    var newnodes = gnodes.enter().append("g")      .attr("class", "node")      .attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })       .call(drag)      .on('mouseover', onmouseover)      .on('mouseout', onmouseout);  newnodes.append("circle")     .attr("cx", 0)     .attr("cy", 0)     .attr("r", radius);  newnodes.append("image")     .attr("xlink:href", getimage)     .attr("x", -radius/2)     .attr("y", -radius/2)     .attr("width", radius + "px")     .attr("height", radius + "px"); 

in onmouseover want change colour of highlighted circle, can not item data receive:

function onmouseover(d, i) {    var c1 = d.select("circle"); // error    var c2 = i.select("circle"); // error    var c3 = d.selectall("circle"); // error    var c4 = i.selectall("circle"); // error  } 

what way child node d3?

d data object , i index. both not d3 instances provide access of d3 select functions.
try this:

myelement.on('mouseenter', function(d,i) {     d3.select(this).select('circle'); });