Q:

How to get the input from the json to draw the graph

<html>
<head>
<title>JS Charts</title>
</head>
<script type="text/javascript">
  var Apple = [];
  var Samsung = [];
  var Nokia = [];
  function loadJSON(callback) {
    var xobj = new XMLHttpRequest();
    xobj.overrideMimeType("application/json");
    xobj.open('GET', 'https://api.myjson.com/bins/1igag', true);
    xobj.onreadystatechange = function() {
        if (xobj.readyState == 4 && xobj.status == "200") {
            callback(xobj.responseText);
        }
    }
    xobj.send(null);
}
loadJSON(function(response) {
  var response;
  var field=JSON.parse(response);
  for (var i = 0; i < field.length; i++) {
        Apple.push(field[i].xxx);
        Samsung.push((field[i].xxx)+10);
        Nokia.push((field[i].xxx)-30);
      }
    sections = 12;
 Val_max = 130;
 Val_min = -40;
 var stepSize = 10;
 var columnSize = 50;
 var rowSize = 50;
 var margin = 10;
 var xAxis = [" ", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"] 
 canvas = document.getElementById("canvas");
 context = canvas.getContext("2d");
 context.fillStyle = "#0099ff"
 context.font = "20 pt Verdana"
 yScale = (canvas.height - columnSize - margin) / (Val_max - Val_min);
 xScale = (canvas.width - rowSize) / sections;
 context.strokeStyle="#009933"; // color of grid lines
 context.beginPath();
    // print Parameters on X axis, and grid lines on the graph
 for (i=1;i<=sections;i++) {
  var x = i * xScale;
  context.fillText(xAxis[i], x,columnSize - margin);
  context.moveTo(x, columnSize);
  context.lineTo(x, canvas.height - margin);
 }
    // print row header and draw horizontal grid lines
 var count =  0;
 for (scale=Val_max;scale>=Val_min;scale = scale - stepSize) {
  var y = columnSize + (yScale * count * stepSize); 
  context.fillText(scale, margin,y + margin);
  context.moveTo(rowSize,y)
  context.lineTo(canvas.width,y)
  count++;
 }
 context.stroke();
 context.translate(rowSize,canvas.height + Val_min * yScale);
 context.scale(1,-1 * yScale);
  // Color of each dataplot items
 context.strokeStyle="#FF0066";
 plotData(Apple);
 context.strokeStyle="#9933FF";
 plotData(Samsung);
  context.strokeStyle="#000";
 plotData(Nokia);
function plotData(dataSet) {
 context.beginPath();
 context.moveTo(0, dataSet[0]);
 for (i=1;i<sections;i++) {
  context.lineTo(i * xScale, dataSet[i]);
 }
 context.stroke();
}
    });
</script>
<body>
<div align="center">
<h2>Monthly Profits of Companies(in million $)</h2>
<canvas id="canvas" height="400" width="650">
</canvas>
<br>
 <!--Legends for Dataplot -->
<span style="color:#FF0066"> Apple </span>  
<span style="color:#9933FF"> Samsung</span>  
<span style="color:#000"> Nokia </span>
</div>
</body>
</html>

Hi. I need to plot a linear graph. Here I have taken the sample. Now I need to take the data for both x and y from the json file. How I can do that. I am not allowed to use any library or API only HTML,CSS and Javascript are allowed.Can anyone please tell me. My json data looks like
[{"aa":{  
   "total_visits":"925",
   "2017-07-29":{  
      "visits":38,
      "leads":0
   },

   "total_leads":13
},
"bb":{  
   "total_visits":"144",
   "2017-07-29":{  
      "visits":1,
      "leads":0
   },
          "total_leads":1
},
"cc":{  
   "last_recorded":"2017-07-29",
   "total_visits":"1386",
   "2017-07-29":{  
      "visits":41,
      "leads":0
   },

   "total_leads":12
},
"dd":{  
   "total_visits":"2364",
   "2017-07-29":{  
      "visits":55,
      "leads":2.1
   },

   "total_leads":59
},
"ee":{  

   "2017-07-29":{  
      "visits":44,
      "leads":0
   },

   "total_leads":37
},
"ff":{  

   "total_leads":2
},
"gg":{  

   "total_leads":1
},
"hh":{  

   "total_visits":"115",

   "2017-07-29":{  

      "visits":2,
      "leads":0
   },
   "package_id":"2",
   "total_leads":3
},
"ii":{  

   "total_visits":"2213",

   "2017-07-29":{  

      "visits":94,
      "leads":0
   },

   "total_leads":87
}
}]

I need to take the total_visits(or)visits(x-axis) and total_leads(or)leads(y-axis) and plot the graph. Thanks in advance. 

A:

Try this code
Edited plotData function for plotting x,y-axis values
function plotData(xVisits,yLeads) {
    context.beginPath();
    context.moveTo(xVisits, yLeads);
    for (i=1;i<xVisits.length;i++) {
        context.lineTo(xVisits[i], yLeads[i]);
    }
    context.stroke();
}

<script type="text/javascript">
  var visits = [];
  var leads = [];
  function loadJSON(callback) {
    var xobj = new XMLHttpRequest();
    xobj.overrideMimeType("application/json");
    xobj.open('GET', 'https://api.myjson.com/bins/17x8l1', true);
    xobj.onreadystatechange = function() {
        if (xobj.readyState == 4 && xobj.status == "200") {
            callback(xobj.responseText);
        }
    }
    xobj.send(null);
}
loadJSON(function(response) {
  var response;
  var field=JSON.parse(response);
  for (var i = 0; i < field.length; i++) {
  var $this=field[i];
       for (var key in $this) {
          if ($this.hasOwnProperty(key)) {
            var val = $this[key];
            visits.push(val.total_visits);
            leads.push(val.total_leads);
          }
      }
      }
    sections = 12;
 Val_max = 130;
 Val_min = -40;
 var stepSize = 10;
 var columnSize = 50;
 var rowSize = 50;
 var margin = 10;
 var xAxis = [" ", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"] 
 canvas = document.getElementById("canvas");
 context = canvas.getContext("2d");
 context.fillStyle = "#0099ff"
 context.font = "20 pt Verdana"
 yScale = (canvas.height - columnSize - margin) / (Val_max - Val_min);
 xScale = (canvas.width - rowSize) / sections;
 context.strokeStyle="#009933"; // color of grid lines
 context.beginPath();
    // print Parameters on X axis, and grid lines on the graph
 for (i=1;i<=sections;i++) {
  var x = i * xScale;
  context.fillText(xAxis[i], x,columnSize - margin);
  context.moveTo(x, columnSize);
  context.lineTo(x, canvas.height - margin);
 }
    // print row header and draw horizontal grid lines
 var count =  0;
 for (scale=Val_max;scale>=Val_min;scale = scale - stepSize) {
  var y = columnSize + (yScale * count * stepSize); 
  context.fillText(scale, margin,y + margin);
  context.moveTo(rowSize,y)
  context.lineTo(canvas.width,y)
  count++;
 }
 context.stroke();
 context.translate(rowSize,canvas.height + Val_min * yScale);
 context.scale(1,-1 * yScale);
  // Color of each dataplot items
 context.strokeStyle="#FF0066";
 plotData(visits,leads);
function plotData(xVisits,yLeads) {
 context.beginPath();
 context.moveTo(xVisits, yLeads);
 for (i=1;i<xVisits.length;i++) {
  context.lineTo(xVisits[i], yLeads[i]);
 }
 context.stroke();
}
    });
</script>
<body>
<div align="center">
<h2>Monthly Profits of Companies(in million $)</h2>
<canvas id="canvas" height="400" width="650">
</canvas>
<br>
 <!--Legends for Dataplot -->
<span style="color:#FF0066"> Visits Vs Leads</span>  
</div>
</body>

updated

you should edit json data to show a linear graph.

var X = [];
var Y = [];
var data = [];
function loadJSON(callback) {
    var xobj = new XMLHttpRequest();
    xobj.overrideMimeType("application/json");
    xobj.open('GET', 'https://api.myjson.com/bins/gzdjd', true);
    xobj.onreadystatechange = function() {
        if (xobj.readyState == 4 && xobj.status == "200") {
            callback(xobj.responseText);
        }
    }
    xobj.send(null);
}
loadJSON(function(response) {
 var response;
 var field=JSON.parse(response);
 var values=[];
 for (var i = 0; i < field.length; i++) {
  var $this=field[i];
  for (var key in $this) {
    if ($this.hasOwnProperty(key)) {
   var val = $this[key];
   values.push({"X":val.total_visits,"Y":val.total_leads});
    }
  }
 }
    data=({"values":values});
    var graph;
 var xPadding = 30;
 var yPadding = 30;
 var sections = 12;
 var Val_max = 130;
 var Val_min = -40;
 var stepSize = 10;
 var columnSize = 50;
 var rowSize = 50;
 var margin = 10;

 function getMaxY() {
  var max = 0;
  for(var i = 0; i < data.values.length; i ++) {
   if(data.values[i].Y > max) {
    max = data.values[i].Y;
   }
  }
  max += 10 - max % 10;
  return max;
 }

 function getMaxX() {
  var max = 0;
  for(var i = 0; i < data.values.length; i ++) {
   if(data.values[i].X > max) {
    max = data.values[i].X;
   }
  }
  max += 10 - max % 10;
  return max;
 }

 function getXPixel(val) {
  return ((graph.width - xPadding) / getMaxX()) * val + (xPadding * 1.5);
 }

 function getYPixel(val) {
  return graph.height - (((graph.height - yPadding) / getMaxY()) * val) - yPadding;
 }

 graph = document.getElementById("canvas");
 var c = graph.getContext('2d');            

 c.lineWidth = 1;
 c.strokeStyle = '#333';
 c.font = 'italic 8pt sans-serif';
 c.textAlign = "center";

 c.beginPath();
 c.moveTo(xPadding, 0);
 c.lineTo(xPadding, graph.height - yPadding + 20);
 c.lineTo(graph.width, graph.height - yPadding + 20);
 c.stroke();

 for(var i = 0; i < data.values.length; i ++) {
  c.fillText(data.values[i].X, getXPixel(data.values[i].X), graph.height - yPadding + 30);
 }

 c.textAlign = "right"
 c.textBaseline = "middle";

 for(var i = 0; i < getMaxY(); i += 10) {
  c.fillText(i, xPadding - 10, getYPixel(i));
 }

 c.strokeStyle = '#f00';

 c.beginPath();
 c.moveTo(getXPixel(data.values[0].X), getYPixel(data.values[0].Y));
 for(var i = 1; i < data.values.length; i ++) {
  c.lineTo(getXPixel(data.values[i].X), getYPixel(data.values[i].Y));
 }
 c.stroke();

 c.fillStyle = '#333';

 for(var i = 0; i < data.values.length; i ++) {  
  c.beginPath();
  c.arc(getXPixel(data.values[i].X), getYPixel(data.values[i].Y), 4, 0, Math.PI * 2, true);
  c.fill();
 }
 var yScale = (graph.height - columnSize - margin) / (Val_max - Val_min);
 var xScale = (graph.width - rowSize) / sections;
 c.strokeStyle="#009933"; // color of grid lines
 c.beginPath();

 for (i=1;i<=sections;i++) {
  var x = i * xScale;
  //c.fillText(xAxis[i], x,columnSize - margin);
  c.moveTo(x - 18, columnSize);
  c.lineTo(x - 18, graph.height - margin);
 }

 var count =  0;
 for (scale=Val_max;scale>=Val_min;scale = scale - stepSize) {
  var y = columnSize + (yScale * count * stepSize); 
  //c.fillText(scale, margin,y + margin);
  c.moveTo(rowSize - 18,y)
  c.lineTo(graph.width,y)
  count++;
 }
 c.stroke();
});
<div align="center">
<h2>Monthly Profits of Companies(in million $)</h2>
<canvas id="canvas" height="400" width="650">
</canvas>
<br>
 <!--Legends for Dataplot -->
<span style="color:#FF0066"> Visits Vs Leads</span>  
</div>

