JavaScript Interview Question #146

What is optional catch binding?

Generators, Browser Storage, Security & Advanced Runtime Concepts Senior Advanced

Quick Interview Answer

When a catch block does not need the thrown error value, JavaScript allows the catch parameter to be omitted. This is called optional catch binding.

Detailed Explanation

When a catch block does not need the thrown error value, JavaScript allows the catch parameter to be omitted. This is called optional catch binding.

Use it only when the error details are genuinely irrelevant. In production systems, ignoring useful error context can make troubleshooting more difficult, so many catch blocks should still capture and appropriately log or propagate the error.

Code Example

function tryParse(json) {
    try {
        return JSON.parse(json);
    } catch {
        return null;
    }
}

console.log(tryParse('{"id":1}'));
console.log(tryParse("invalid"));