Web_Dev_Grad

JavaScript is a flexible language, but like any programming language, code can sometimes go wrong. That's where try...catch comes in. It helps you handle errors gracefully, without crashing your whole program. try...catch is used to run code that might fail and provide a fallback response if an exception is thrown. The syntax is a try block of code followed by a catch block and an optional finally block that runs regardless of an error.

try {
    // Code that may throw an error
} catch (error) {
    // Code to run if an error is caught
} finally {
    // Code that always runs, regardless of success or error
}

JavaScript has several built-in error types. Each serves a specific purpose.

The syntax for catching these is to use the instanceof keyword. Typically you would use catch(err) to catch the errors and then repeat “err” in your code block. This is just by convention, but make sure that whatever is the in the catch() parentheses matches your calling of it in the following codeblock.

try {
    // Code that might throw an error
} catch (err) {
    if (err instanceof TypeError) {
        console.error("TypeError caught:", err.message);
    } else if (err instanceof SyntaxError) {
        console.error("SyntaxError caught:", err.message);
    } else if (err instanceof RangeError) {
        console.error("RangeError caught:", err.message);
    } else if (err instanceof EvalError) {
        console.error("EvalError caught:", err.message);
    } else if (err instanceof URIError) {
        console.error("URIError caught:", err.message);
    } else {
        console.error("Generic Error caught:", err.message);
    }
}

You can create your own errors in JavaScript using the throw keyword.

function divide(a, b) {
    if (b === 0) {
        throw new Error("Division by zero is not allowed.");
    }
    return a / b;
}

try {
    console.log(divide(5, 0));
} catch (err) {
    console.warn(err.message);
}