Node server crashes in parsing JSON

Question

Looks like my node server dies in parseJSON. Looked at the logs and the last message was "before parse" and it never printed "after parse". What's strange is that I wrapped JSON.pars with try-catch so I am not sure how it caused the server crashed. Any thoughts?

logger.print("before parse")
parseJSON(data)
logger.print("after parse")

and I have pareJSON catch exception.

function parseJSON(str) {
    try {
        var result = JSON.parse(str);
        return result;
    } catch (err) {
        return null
    }
}

You should `use console.error(err)` in `catch` block and see what happened — thelonglqd, Jan 11 '17 at 04:50
JSON.parse is a synchronous method. So if you are planning to parse big JSON objects use a streaming json parser. Maybe use `json-parse-async`. — Shimon Brandsdorfer, Jan 11 '17 at 05:03
if I try to parse big json object .. would that cause the server to crash? — codereviewanskquestions, Jan 11 '17 at 05:05
First make sure there's no parsing error, by consoling as @thelonglqd suggested, or check out your data at http://jsonlint.com/ — Shimon Brandsdorfer, Jan 11 '17 at 05:09
let's say data can be malformed .. but it should never kill the server? — codereviewanskquestions, Jan 11 '17 at 05:14
another page for checking json format: https://jsonformatter.curiousconcept.com/ — thelonglqd, Jan 11 '17 at 06:33
my point is even if json format is invalid and JSON.parse failed, it should be handled by "catch" clause .. — codereviewanskquestions, Jan 11 '17 at 06:41

score 2 · Accepted Answer · answered Jan 11 '17 at 09:56

If your code crashes in parseJSON then I would try:

try {
  logger.print("before parse")
  parseJSON(data)
  logger.print("after parse")
} catch (e) {
  console.log(e);
}

It is strange because your function should catch the exception but this would show what happens. I would also add:

console.log(data.length);

to see the size of the data.

Also I wrote a module tryjson that parses JSON without throwing exceptions. You can try using it but if your function crashes then maybe my module would not handle it either. Though I'd love to know what actually happens.

Node server crashes in parsing JSON

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