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JSON Formatter

Build Status

Render JSON objects in HTML with a collapsible navigation.

JSON Formatter started as an AngularJS directive. This is pure JavaScript implementation of the same module.

Live Demo


Install via npm

npm install --save json-formatter-js

include json-formatter.js from dist folder in your page.

import JSONFormatter from 'json-formatter-js'

const myJSON = {ans: 42};

const formatter = new JSONFormatter(myJSON);



JSONFormatter(json [, open [, config] ])

json (Object) - required

The JSON object you want to render. It has to be an object or array. Do NOT pass raw JSON string.

open (Number)

Default: 1 This number indicates up to how many levels the rendered tree should expand. Set it to 0 to make the whole tree collapsed or set it to Infinity to expand the tree deeply

config (Object)


  hoverPreviewEnabled: false,
  hoverPreviewArrayCount: 100,
  hoverPreviewFieldCount: 5,
  theme: '',
  animateOpen: true,
  animateClose: true,
  useToJSON: true,
  maxArrayItems: 100,
  exposePath: false

Available configurations:

Hover Preview
  • hoverPreviewEnabled: enable preview on hover.
  • hoverPreviewArrayCount: number of array items to show in preview Any array larger than this number will be shown as Array[XXX] where XXX is length of the array.
  • hoverPreviewFieldCount: number of object properties to show for object preview. Any object with more properties that thin number will be truncated.
  • theme: a string that can be any of these options: ['dark']. Look at src/style.less for making new themes.
  • animateOpen: enable animation when expanding json object. True by default.
  • animateClose: enable animation when closing json object. True by default.
Rendering Options
  • useToJSON: use the toJSON method to render an object as a string as available. Usefull for objects like Date or Mongo's ObjectID that migh make more sense as a strign than as empty objects. True by default.

  • sortPropertiesBy: use the given sorting function to deeply sort the object properties.

  • maxArrayItems: use to split arrays in multiple smaller groups. This value defines the size of each group. If the length of the array is less than this number no groups are created. It's the same behavior of Webkit developer tool's console.

  • exposePath: add an array of keys to each node dataset so it is possible to correlate nodes to the original json.


const formatter = new Formatter({ ... });
depth (Number)

Default: 1 This number indicates up to how many levels the rendered tree should open. It allows use cases such as collapse all levels (with value 0) or expand all levels (with value Infinity).


Install the dependencies:

npm install

Run the dev server

npm start

Running tests


npm test