Answers for "ERROR TypeError: Converting circular structure to JSON - Solution"

ERROR TypeError: Converting circular structure to JSON - Solution

ficheiro.html
<form novalidate #formulario="ngForm">

<pre>{{ formulario.form | json }}</pre>

</form>

Result : ficheiro.html

{
  "_hasOwnPendingAsyncValidator": false,
  "_parent": null,
  "pristine": true,
  "touched": false,
  "_onDisabledChange": [],
  "_rawValidators": null,
  "_rawAsyncValidators": null,
  "_composedValidatorFn": null,
  "_composedAsyncValidatorFn": null,
  "controls": {},
  "valueChanges": {
    "_isScalar": false,
    "observers": [],
    "closed": false,
    "isStopped": false,
    "hasError": false,
    "thrownError": null,
    "__isAsync": false
  },
  "statusChanges": {
    "_isScalar": false,
    "observers": [],
    "closed": false,
    "isStopped": false,
    "hasError": false,
    "thrownError": null,
    "__isAsync": false
  },
  "status": "VALID",
  "value": {},
  "errors": null
}