title: how to read a text file by lines with d3.js (like readlines in python)
body: <p>I want to plot a picture with D3.
  The data is from text file
  like this:
  a.txt:</p>
  
  <pre><code>1 200
  2 300
  3 220
  </code></pre>
  
  <p>I try to read the file in this way</p>
  
  <pre><code>    d3.text("850191387_full_info.txt",function(error,data)
  {
    if(error)
      return console.error(error);
    d3.select("body")
      .append("p")
      .text(data);
  });  
  </code></pre>
  
  <p>But it can only appear the whole data in web page.
  How can I plot a simple line chart with this txt file?
  the first column as x variable, and the second column as y variable</p>