尝试/捕获以检查json不起作用

Question

I want to check if a string received is JSON and I tried the following code:

try {
    JSON.parse(-10); // Same for "-10"
}catch(e) {
    console.log('inside catch');
}

The code never goes inside the catch block! Why is it so?

Answer 1

A plain value is valid JSON . That's why you're not getting 'inside catch' logged.

 document.write(JSON.parse(-10)); 

This isn't valid JSON, however:

 try { JSON.parse('{'); }catch(e) { document.write('inside catch'); } 

As you can see, the try / catch is working just fine.

Answer 2

I think -10 is valid to JSON.parse

JSON.parse('{}');              // {}
JSON.parse('true');            // true
JSON.parse('"foo"');           // "foo"
JSON.parse('[1, 5, "false"]'); // [1, 5, "false"]
JSON.parse('null');            // null

 try { var a = JSON.parse("{[]]]["); // Same for "-10" console.log(a); }catch(e) { console.log('inside catch'); }