[Solved]-d3.js on event + jshint possible strict violation-d3.js

Use function expression instead of declaration like

var mouseover = function () {
var val = d3.select(this).attr('val');

div.transition()
    .duration(200)
    .style('opacity', 0.9);

div.html(val + ' Servers')
    .style('left', (d3.event.pageX + 20) + 'px')
    .style('top', (d3.event.pageY - 20) + 'px');

d3.select(this).style('fill', 'brown');
};