What's the difference in using toString() compared to JSON.stringify()?

Question

In both the cases I get in output the content of the object:

alert(JSON.stringify(obj)); 

or

alert(obj.toString()); 

so... what's the difference? what are the advantages or disadvantages of each one?

Are there practical examples to show the difference?

Answer 1

Unless you have a custom object with custom .toString method returning JSON.stringify of that object, there is no obj that would give obj.toString() == JSON.stringify(obj).

When obj is an array like [1,2,3] then .toString() gives:

"1,2,3" 

And JSON.stringify:

"[1,2,3]" 

These are close but not quite the same, the JSON serialized one has no ambiguity with commas and directly runs as Javascript or can be parsed as JSON.

See:

["1,",2,3].toString(); //"1,,2,3" ... so you can't just split by comma and get original array //it is in fact impossible to restore the original array from this result  JSON.stringify(["1,",2,3]) //'["1,",2,3]' //original array can be restored exactly 

Answer 2

for an object say

obj = { a: 'a', '1': 1 } 

obj.toString() gives

"[object Object]" 

JSON.stringify(obj) gives

"{"1":1,"a":"a"}" 

For .toString(), a default value is returned when the argument type is an object. JSON.stringify on the other hand returns JSON text, which can be converted back into a JSON object by using JSON.parse