如何使用d3js的data方法解析对象数组并将其显示在工具提示中？

var svg = d3.select("div")
            .append("svg")
            .attr("width", width)
            .attr("height", height);

var data = [
  { name: "Alice", age: 25 },
  { name: "Bob", age: 30 },
  { name: "Charlie", age: 35 }
];

var circles = svg.selectAll("circle")
                .data(data);

circles.enter()
       .append("circle")
       .attr("cx", function(d, i) { return i * 50 + 50; })
       .attr("cy", 50)
       .attr("r", 20);

circles.on("mouseover", function(d) {
          tooltip.style("visibility", "visible")
                 .text(d.name + ": " + d.age);
        })
        .on("mousemove", function() {
          tooltip.style("top", (d3.event.pageY - 10) + "px")
                 .style("left", (d3.event.pageX + 10) + "px");
        })
        .on("mouseout", function() {
          tooltip.style("visibility", "hidden");
        });

circles.attr("fill", "steelblue")
       .attr("stroke", "white")
       .attr("stroke-width", 2)
       .on("click", function(d) {
         // 点击事件处理逻辑
       });