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javascriptfunctionreturnundefined

Return Lastname when not definded

I'm studying JavaScript combining functions. Supposed I have firstname and lastName as two arguments of my function. I want the console to display Doe when lastname is undefinded . Here is my code but it printed out undefined. Any idea? Thank you!

let name = 'John'

function greetByDefault(firstname,lastname){
     return 'Hi ' + firstname +' '+ lastname + '!';
 }
  if (lastname === undefined){
        return 'Doe';
 }

console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));

I want the console output to be:

Hi Jane Doe! Hi John Doe!

Solution

  • You have to put everything in function

    let name = 'John'
function greetByDefault(firstname,lastname){
  if (lastname === undefined){
      lastname = 'Doe';
  }
     return 'Hi ' + firstname +' '+ lastname + '!';
 }

console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));