Test to ensure correct behaviour of replacer functions in JSON.stringify On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS JSON.stringify(object, returnUndefined) is undefined. PASS JSON.stringify(array, returnUndefined) is undefined. PASS JSON.stringify(object, returnObjectFor1) is '{"0":0,"1":{},"2":2}' PASS JSON.stringify(array, returnObjectFor1) is '[0,{},2,null]' PASS JSON.stringify(object, returnArrayFor1) is '{"0":0,"1":[],"2":2}' PASS JSON.stringify(array, returnArrayFor1) is '[0,[],2,null]' PASS JSON.stringify(object, returnUndefinedFor1) is '{"0":0,"2":2}' PASS JSON.stringify(array, returnUndefinedFor1) is '[0,null,2,null]' PASS JSON.stringify(object, returnFunctionFor1) is '{"0":0,"2":2}' PASS JSON.stringify(array, returnFunctionFor1) is '[0,null,2,null]' PASS JSON.stringify(object, returnNullFor1) is '{"0":0,"1":null,"2":2}' PASS JSON.stringify(array, returnNullFor1) is '[0,null,2,null]' PASS JSON.stringify(object, returnStringForUndefined) is '{"0":0,"1":1,"2":2,"3":"undefined value"}' PASS JSON.stringify(array, returnStringForUndefined) is '[0,1,2,"undefined value"]' PASS JSON.stringify(object, returnCycleObjectFor1) threw exception TypeError: JSON.stringify cannot serialize cyclic structures.. PASS JSON.stringify(array, returnCycleObjectFor1) threw exception TypeError: JSON.stringify cannot serialize cyclic structures.. PASS JSON.stringify(object, returnCycleArrayFor1) threw exception TypeError: JSON.stringify cannot serialize cyclic structures.. PASS JSON.stringify(array, returnCycleArrayFor1) threw exception TypeError: JSON.stringify cannot serialize cyclic structures.. PASS successfullyParsed is true TEST COMPLETE