Example of Mouseover/Mouseout

JavaScript

var dataset = ["mary","goes"];
svg = d3.select("body").append("svg");

svg.selectAll('text')
    .data(dataset)
    .enter()
    .append('text')
    .attr('x',function(d,i) {return i * 50;})
    .attr('y',20)
    .text(function(d) {
        return d;
    })
    .on('mouseover',mouseover)
    .on('mouseout',mouseout);

function mouseover(d) {
    d3.select(this).style("opacity",0);
};

function mouseout(d) {
    d3.select(this).style("opacity",1);
    var scale = d3.scaleLinear();
scale.domain([0, 300])
scale.range([0, 30]);
console.log(scale(2.5));
};