console 命令行工具 X clear

console

var bSet   = [3,6,9,12,15];

var update = d3.select('body').selectAll('p')
               .data(bSet)
               .text(d=>d);

var enterElement = update.enter();    
enterElement.each(d=> {
console.log("enterElement:",d);
});

var bSet   = [3];

var update = d3.select('body').selectAll('p')
               .data(bSet)
               .text(d=>d);

var exitElement = update.exit();

exitElement.each(d=> {
console.log("exitElement:",d);
});

<html> 
  <head> 
      <meta charset="utf-8"> 
      <script src="https://d3js.org/d3.v5.min.js"></script>
  </head> 
    <body> 
        <p></p>
        <p></p>
        <p></p>
    </body> 
</html>