A "JSON object" doesn't make sense : JSON is an exchange format based on the structure of Javascript object declaration.
If you want to convert your javascript object to a json string, use JSON.stringify(yourObject)
;
If you want to create a javascript object, simply do it like this :
var yourObject = {
test:'test 1',
testData: [
{testName: 'do',testId:''}
],
testRcd:'value'
};