Create a JSON representation of an Image object using FabricJS

This article shows how to create a JSON representation of an image object using FabricJS. We can create an Image object by creating an instance of Fabric.Image . Since it is one of the basic elements of FabricJS, we can also easily customize it by applying properties like angle, opacity, etc. To create a representation of a JSON Image object, we use the toJSON method.

grammar

toJSON(propertiesToInclude: Array): Object

parameter

propertiesToInclude - This parameter accepts an Array containing any properties we may wish to additionally include in the output. This parameter is optional.

Use the toJSON method

example

Take a look at a code example to see the output logged when using the toJSON method. In this case, a JSON representation of the image instance is returned.

<!DOCTYPE html>
<html>
<head>
   <!-- Adding the Fabric JS Library-->
   <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
   <h2>Using the toJSON method</h2>
   <p>
      You can open console from dev tools and see that the logged output contains the JSON representation of the image instance
   </p>
   <canvas id="canvas"></canvas>
   <img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
      
      // Initiating the image element
      var imageElement = document.getElementById("img1");
      
      // Initiate an Image object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
      });
      
      // Add it to the canvas
      canvas.add(image);
      
      // Using the toJSON method
      console.log(
         "JSON representation of the Image instance is: ",
         image.toJSON()
      );
   </script>
</body>
</html>

Use the toJSON method to add additional properties

example

Take another look at the code example to see how to use the toJSON method. In this example, we added a custom attribute called "name". We can pass specific property as second parameter in options to fabric.Image instance object and pass the same key to toJSON method.

<!DOCTYPE html>
<html>
<head>
   <!-- Adding the Fabric JS Library-->
   <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
   <h2>Using toJSON method to add additional properties</h2>
   <p>
      You can open console from dev tools and see that the logged output contains added property called name
   </p>
   <canvas id="canvas"></canvas>
   <img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
      
      // Initiating the image element
      var imageElement = document.getElementById("img1");
      
      // Initiate an Image object with name key
      // passed in options object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
         name: "Image instance",
      });
      
      // Add it to the canvas
      canvas.add(image);
      
      // Using the toJSON method
      console.log(
         "JSON representation of the Image instance is: ",
         image.toJSON(["name"])
      );
   </script>
</body>
</html>