Question

How to handle invalid argument in JavaScript

Answer 1

function processNumber(num) {
    if (typeof num !== 'number' || num < 0) {
        console.error("Invalid input: Must be a positive number.");
        return;
    }
    
    console.log("input ok:", num);
}

processNumber(3);  
processNumber(-7); 



/*
run:

input ok: 3
Invalid input: Must be a positive number.

*/

 

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Answer 2

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 (error) {
    console.error("Error:", error.message);
}



/*
run:

ERROR!
Error: Division by zero is not allowed.

*/

 

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Answer 3

function say(name) {
    name = name || "Guest"; // Default to "Guest" if falsy
    console.log("Hello, " + name + "!");
}

say(); 
say("Bob"); 



/*
run:

Hello, Guest!
Hello, Bob!

*/

 

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Answer 4

function addNumbers(a, b) {
    if (typeof a !== "number" || typeof b !== "number") {
        throw new TypeError("Both arguments must be numbers.");
    }
    return a + b;
}

console.log(addNumbers(6, "abc")); // Throws TypeError



/*
run:

ERROR!
main.js:3
        throw new TypeError("Both arguments must be numbers.");
        ^

TypeError: Both arguments must be numbers.
    at addNumbers (main.js:3:15)

*/

 

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