小编lov*_*ong的帖子

$(document).on("click", "#save", function() {
  html2canvas(
    $("body"), {
      onrendered: function(canvas) {
        $("#result_here").append(canvas);
        var data = new FormData();
        data.append("data", "the_text_you_want_to_save");

        var xhr = (window.XMLHttpRequest) ? new XMLHttpRequest() : new activeXObject("Microsoft.XMLHTTP");
        xhr.open('post', 'save_file.php', true);
        xhr.send(data);
      }
    }
  );
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.min.js"></script>

<div id="canvas" style="border:1px solid red; width: 300px; heght:300px; ">
  <p>hello
    <p>
      <p>??????</p>
</div>

<div id="result_here" stlye="border:1px solid blue;"></div>

<button id="save">SAVE</button>