fileIO.js

function initFileIO() {
  // Check for the various File API support.
  if (!(window.File && window.FileReader && window.FileList && window.Blob)) {
    alert("The File APIs are not fully supported in this browser.");
    return -1;
  }
  if (DEBUG) {
    console.log("Initialize File IO complete.");
  }

  document
    .getElementById("fileInputs")
    .addEventListener("change", handleFileSelect, false);
}
var JSONdata;
function handleFileSelect(evt) {
  var files = evt.target.files; // FileList object

  // files is a FileList of File objects. List some properties.
  var output = [];
  for (var i = 0, f; (f = files[i]); i++) {
    output.push(
      "<li><strong>",
      f.name,
      "</strong> (",
      f.type || "n/a",
      ") - ",
      f.size,
      " bytes, last modified: ",
      f.lastModifiedDate.toLocaleDateString(),
      "</li>"
    );

    var reader = new FileReader();

    reader.onload = function (e) {
      var text = e.target.result;
      try {
        jsData = parseInputText(text);
      } catch (e) {
        ERROR = e; // For console access
        alert("Couldn't Parse JSON from file : ", e.name, " : ", e.message);
        console.log("ERROR parsing: ", e.name, " : ", e.message);
        return -1;
      }

      loadSysFromJSON(jsData);
      if (DEBUG) {
        console.log("JSON FILE LOADED: ", jsData.name);
      }
    };
    reader.onerror = errorHandler;

    reader.readAsText(f);
  }
  document.getElementById("fileList").innerHTML =
    "<ul>" + output.join("") + "</ul>";
}

function errorHandler(evt) {
  switch (evt.target.error.code) {
    case evt.target.error.NOT_FOUND_ERR:
      alert("File Not Found!");
      break;
    case evt.target.error.NOT_READABLE_ERR:
      alert("File is not readable");
      break;
    case evt.target.error.ABORT_ERR:
      break; // noop
    case evt.target.error.SECURITY_ERR:
      alert(
        "File Security Error, If running locally (ie. 'file://' then need --allow-file-access-from-files for browser)"
      );
      break;
    default:
      alert("An error occurred reading this file.");
  }
  if (DEBUG) {
    console.log(
      "FILE LOADED UNSUCCESSFULLY: Error Code ",
      evt.target.error.code
    );
  }
}

function parseInputText(text) {
  lines = text.split("\n");
  for (var i = 0; i < lines.size; i++) {
    console.log(i, ": ", lines[i]);
  }
  return JSON.parse(text);
}

function loadSysFromJSON(jsonData) {
  // Constants
  MINMASS =
    typeof jsData.Constants.MINMASS != "undefined"
      ? jsData.Constants.MINMASS
      : MINMASS;
  MAXMASS =
    typeof jsData.Constants.MAXMASS != "undefined"
      ? jsData.Constants.MAXMASS
      : MAXMASS;
  G = typeof jsData.Constants.G != "undefined" ? jsData.Constants.G : G;
  GFACTOR =
    typeof jsData.Constants.GFACTOR != "undefined"
      ? jsData.Constants.GFACTOR
      : GFACTOR;
  ETA = typeof jsData.Constants.ETA != "undefined" ? jsData.Constants.ETA : ETA;
  if (DEBUG) {
    console.log("MINMASS: ", MINMASS);
    console.log("MAXMASS: ", MAXMASS);
    console.log("G: ", G);
    console.log("GFACTOR: ", GFACTOR);
    console.log("ETA: ", ETA);
  }

  // Bodies
  for (i = 0; i < jsData.Bodies.N; i++) {
    var b = jsData.Bodies.BodyData[i];
    //addBody(x,y,vx,vy,m)
    addBody(b[1], b[2], b[3], b[4], b[0]);
  }
  refreshGraphics();
}