decircularize

Remove circular dependencies. It also functions as a deep-copy, to ensure that the input is never mutated and that the output can be trusted, even if there are no issues with circular structures.

Usage

The default behavior replaces the dependencies with a string suitable for debugging.

import decircularize from 'decircularize'
 
var obj = {
    a: 1,
    b: { something: 2 }
}
obj.b.bad = obj
obj.b.alsoBad = obj.b
 
JSON.stringify(obj) // explodes
 
JSON.stringify(decircularize(obj), null, 2)
/* returns
{
  a: 1,
  b: {
    something: 2,
    bad: '[Circular to: <root>]',
    alsoBad: '[Circular to: <root>.b]'
  }
}
*/

This can easily be overridden for any custom need. For example, imagine a REST API where each entity have an id prop that uniquely identifies it:

import decircularize from 'decircularize'
 
var obj = {
    id: '123',
    b: {
        id: 'abc',
        entities: [ 2 ]
    }
}
obj.b.entities.push(obj.b)
 
decircularize(obj, {
    onCircular: (object, otherPath, offendingPath) => {
        assert(object === obj.b)
 
        // In this instance, otherPath equals [ '<root>', 'b' ]
        // and offendingPath equals [ '<root>', 'b', 'entities', 1 ]
 
        return { id: object.id }
    }
})
/* returns
{
    a: 1,
    b: {
        id: 'abc',
        entities: [
            2,
            { id: 'abc' }
        ]
    }
}
*/