Hello I am a newbie learning Js I am trying to learn about recursion but I stuck in here
var isEven = (number) =>{
number = Number(number)
if(number === 0){
console.log('it is even')
return true;
}
else if(number === 1){
return false;
}
else{
number = number - 2;
isEven(number);
}
}
console.log(isEven(50) === true)
why the end result becomes undefined? Thank you for the help
Add return in recursion call:
function isEven(number){
number = Number(number)
if(number === 0){
console.log('it is even');
return true;
}
else if(number === 1){
return false;
}
else{
number = number - 2;
return isEven(number);
}
}
console.log(isEven(50));You must use return in recursion call .If u do not use return the isEven(50) function will run but do not return isEven(48) so your function isEven(50) get undefined.So always use return. Example
function factorial( n ) {
if ( n === 1 ) {
return 1;
}
return n * factorial( n - 1 );
}
In above example you can when we call factorial(n-1); it will return (n-1)*factorial(n-2); but if u remove the return then result is undefined as factorial(n-1); do not return anything. Always remember in recursion focus is on returning function again and again till we get the result.
return isEven(number);