CODEWITHSUNDEEP
javascriptnode.js
user109321948492842303
user109321948492842303

Reputation: 135

NULL if statement excecuted wrong in node.js

I'm using Node.js, I've made a function that looks like this:

function makeTitleWith(name) {
   if (name === null) {
         return "Hello, welcome to my app!"
   } else {
         return "Hello, welcome " + name + "!"
   }
}

And when I call it with a variable thats null, it returns "Hello, welcome null!". I'm new pretty new to JS, and this is driving me insane. I've also tried == instead of === but it makes no difference.

Upvotes: 0

Views: 500

Answers (2)

Sagar Agrawal
Sagar Agrawal

Reputation: 657

I would recommend you can modify the above code like this (more like defensive coding) and expect/enforce the caller to send the string value as input param to the function.

if(typeof name == "string"){
    return "Hello, welcome " + name + "!";
}
return "Hello, welcome to my app!";

Also note, if the caller is calling the function with null or empty object, in both the cases, typeof operator returns object. So based on your case I don't think that the method was called with null or empty object.

Upvotes: 0

T.J. Crowder
T.J. Crowder

Reputation: 1075249

when I call it with a variable thats null, it returns "Hello, welcome null!"

That means you're not calling it with name set to null, you're calling it with name set to "null" (or an unlikely second possibility I'll cover later). "null" is not equal to null (either == or ===).

Example:

function makeTitleWith(name) {
   if (name === null) {
         return "Hello, welcome to my app!"
   } else {
         return "Hello, welcome " + name + "!"
   }
}
console.log(makeTitleWith("null"));
// or more likely:
var n = String(null);
console.log(makeTitleWith(n));

You probably want to fix where you're calling it, since that "null" is probably the result of converting null to string.

The unlikely second possibility: You're calling it with name set to an object that, when converted to string, converts to "null", like this:

function makeTitleWith(name) {
   if (name === null) {
         return "Hello, welcome to my app!"
   } else {
         return "Hello, welcome " + name + "!"
   }
}

var n = {
    toString() {
        return "null";
    }
};
console.log(makeTitleWith(n));

I very much doubt that's what's going on.

Upvotes: 2

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