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JavaScript

Shane McC
Shane McC
3,005 Points
Posted by Shane McC
Shane McC
3,005 Points

Why am I returning undefined?

Hi Everyone,

I was playing around with javascript and I don't understand why I'm returning "undefined" with the syntax below. What am I doing wrong?

Thanks

var from = function(state, city, name){
console.log("Hi, I'm " + name + ". I'm from " + city + ", "+ state );
};

console.log(from("Massachusetts", "Boston","Bob"));

1 Answer

Sean T. Unwin
Sean T. Unwin
28,690 Points
Sean T. Unwin
Sean T. Unwin
28,690 Points

It is because your function is not returning anything, but simply outputting some data to the console.

As per the ES5 [[Call]] internal method for a Function object spec (specifically points 5 and 6), if a function does not explicitly return anything it will return undefined.

One way to refactor your function would be: 

var from = function(state, city, name){
  /*
   * Create a local variable, mainly to ease readability
   * and to understand what we're attempting to do
   */
  var rStr = "Hi, I'm " + name + ". I'm from " + city + ", " + state;

   /* Return the string */
  return rStr;
};
// Call your function using console.log
console.log(from("Massachusetts", "Boston", "Bob"));

I hope that helps to clarify.

Shane McC
Shane McC
3,005 Points
Shane McC
Shane McC
3,005 Points

Thanks Sean, appreciate the help