JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [  
   {  
      "BackgroundColor":null,
      "BaseFormat":"PNG",
      "ColorFormat":"RGB",
      "ColorProfile":null,
      "Density":"300",
      "Extra_param":null,
      "FileFormat":"JPG",
      "PresetId":"2",
      "Resolution":"",
      "Quality":100
   }
];

alert(arr.length);
alert(JSON.stringify(arr).length);