优雅的 JSON.parse 异常处理程序

Question

Say we have a function that calls JSON.parse(someText) multiple times. However, someText is not necessarily error checked, for ex, "foo" could be passed into JSON.parse. When a non JSON value is inputted, I want to return an empty object, {}

Obviously, we can use a try-catch to easily handle this. However, try-catch is ugly and not elegant - is there a quick, simple, one liner way to do something like this?

Answer 1

(this goes to future readers that don't get why this is wrong) You are supposed to catch and handle exceptions, not ignore them. People that develop these functions rely on you catching exceptions to be able to properly react to them breaking. Elegance and beauty are in the eyes of the beholder, and as with any piece of art, you write it so that other people will enjoy it. And everyone gets try...catch blocks.

There's no way to do it in 1 line of code. You can however, do some nasty stuff to bypass exception handling.

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METHOD 1

Manually handle the global onError method.

function handleErr(msg, url, line_no){ 
   var errorMsg = "Error: " + msg + "\n"; 
       errorMsg += "URL: " + url + "\n"; 
       errorMsg += "Line: " + line_no + "\n\n"; 

    console.log(errorMsg); 

 return true;
} 

// Set the global onerror; 
onerror = handleErr;

Now you handle (ie ignore) errors in this function. You can switch it on and off with a bit code. Or you can go bananas and just do a return true; in the handler.

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METHOD 2

Use setTimeout, the thread will die due to the exception but your code will keep executing, also a beautiful ES6 one-liner.

setTimeout(() => JSON.parse("not json: fghfghg"), 0)
console.log("Code still running")

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METHOD 3

For non-mainstream, "Elegant" exception handling you can implement and use Either ( example )

Answer 2

Despite previous comments about exception handling, you can apply a one-liner to achieve your goal. The only catch is numbers and numeric strings; those will be parsed and returned as numbers

 let input = 'someText' let parsedText = (() => { try { return JSON.parse(input) } catch { return {} }}).call() console.info(parsedText) // {} input = '{ "hello": "world" }' parsedText = (() => { try { return JSON.parse(input) } catch { return {} }}).call() console.info(parsedText) // { hello: 'world' } input = '9' parsedText = (() => { try { return JSON.parse(input) } catch { return {} }}).call() console.info(parsedText) // 9