IsEqual

function IsEqual(const aOther: TJSONValue): Boolean;

Example

procedure ScriptEvent(var Value: variant);
var
  LeftValue, RightValue: TJSONString;
begin
  LeftValue := TJSONString.Create;
  RightValue := TJSONString.Create;
  try
    LeftValue.Name := 'status';
    LeftValue.Value := 'ready';
    RightValue.CopyFrom(LeftValue);
    Value := LeftValue.IsEqual(RightValue);
  finally
    RightValue.Free;
    LeftValue.Free;
  end;
end;

Usage

IsEqual compares JSON kind, exact name and current AsString output rather than object identity or complete hidden state.

Additional Technical Info

Parameter	Meaning
aOther	Existing non-nil JSON value to compare. Ownership is unchanged.

IsEqual returns true only when three expressions are equal: immutable ValueType, case-sensitive Name, and the current AsString result. It does not compare object addresses, concrete runtime classes, the private null flag or a retained class-specific payload directly.

Those choices create important equivalence rules:

• a null-marked TJSONString and a non-null empty TJSONString with the same name compare equal because both expose blank AsString;
• cleared scalars with different retained payloads can compare equal when both expose blank text;
• integer and Double nodes share jsNumber, so matching formatted text can compare equal even though their actual classes differ;
• Double values that collapse to the same locale-sensitive formatted text compare equal;
• object order, duplicate fields and serializer defects affect equality because compact object text is compared;
• array item names do not affect equality because array serialization ignores them; and
• top-level names remain significant even though root serialization normally omits them.

The method has no nil guard and reads aOther.ValueType immediately; passing nil raises an access violation. Serialization/conversion exceptions also propagate. Container comparison constructs complete compact strings, so time and temporary memory are proportional to the serialized trees. It is not constant-time, canonical JSON comparison, structural schema comparison or safe for concurrent mutation.

Use explicit IsNull, concrete-class checks and field-by-field logic when null identity, numeric precision, object key order independence or duplicate handling matters.

Created 2026-07-15