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json

Validate that a string parses as valid JSON.

Signature​

NguardValidators.String.json: ValidatorFn

A parameterless validator — used directly without invocation.

Reactive forms​

import { FormControl } from '@angular/forms';
import { NguardValidators } from 'ng-nguard';

const config = new FormControl('', [NguardValidators.String.json]);

Template-driven forms​

<textarea ngModel name="config" nguardJson></textarea>

Error key​

{ json: true }

Notes​

  • Implementation calls JSON.parse and treats any thrown exception as a failure.
  • Both objects ('{}') and primitives ('42', '"hello"') parse as valid JSON.
  • Empty strings fail.
  • Doesn't validate against any schema — use a separate validator if you need structural checks.

See also​

  • regex — for custom shape constraints if you need partial JSON