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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops Refactor Using a Loop

Posted by Toby Emmanuel
Toby Emmanuel
6,782 Points

finding it hard to complete this task

The code below logs all of the even numbers from 2 to 24 to the JavaScript console. However, there's a lot of redundant code here. Re-write this using a loop.

script.js 
console.log(2);
console.log(4);
console.log(6);
console.log(8);
console.log(10);
console.log(12);
console.log(14);
console.log(16);
console.log(18);
console.log(20);
console.log(22);
console.log(24);
index.html 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Loops</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>
Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

It doesn't look like you've written any code yet.

If you really have no idea where to start, you might want to re-watch the video on For Loops.

Toby Emmanuel
Toby Emmanuel
6,782 Points 
  // Not sure if i have to declear a empty variable and then add it into the loop.. help :( 
var argument;
for ( var i = 2; i <= 24; i += 2 ) {
  argument +=  i;
  return argument 
}
console.log( parseInt(argument) );

/*
console.log(2);
console.log(4);
console.log(6);
console.log(8);
console.log(10);
console.log(12);
console.log(14);
console.log(16);
console.log(18);
console.log(20);
console.log(22);
console.log(24);
*/
Toby Emmanuel
Toby Emmanuel
6,782 Points

I've been trying to work it out in workspace and I'm still stuck : s

5 Answers

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

You do appear to have the right idea, and your loop is good, but you have a few issues yet.

  • you need to perform the console.log function inside the loop
  • you'll want to pass the console.log function your "i" variable
  • you can't use return when you're not inside a function
  • you don't need the variable named argument for anything anyway

I'll bet you can get it now.

Johnny Garces
PLUS
Johnny Garces
Courses Plus Student 8,551 Points
Johnny Garces
Johnny Garces
Courses Plus Student 8,551 Points

the break statement is used to jump out of any loop. In this code, the program will console log 0, instead of printing 0-9. 

for(var i = 0; i < 10; i++){
    console.log(i);
    break;
//will console log out 0
}
Kandance Ferguson
Kandance Ferguson
6,271 Points
Kandance Ferguson
Kandance Ferguson
6,271 Points

You declared a variable argument, however argument is undefined -- meaning that you did not assign argument to anything. The first time through the loop, argument = undefined. If you add argument + i --or-- undefined + 2, it will still be undefined, and undefined is not a number.

Return is illegal inside of a loop. It is used with functions.

Think of what you want to do with i. You can write exactly what you want to do with i inside of the loop so that the action happens each time through the loop.

Check out this repl.it link for an example of logging 1 - 10: https://repl.it/C9TZ

Good luck!

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

:x: The use of the return statement doesn't stop the loop, it causes an error.

Outside of a function, return is an illegal statement.

Kandance Ferguson
Kandance Ferguson
6,271 Points
Kandance Ferguson
Kandance Ferguson
6,271 Points

Thanks Steven, updated my answer!

Toby Emmanuel
Toby Emmanuel
6,782 Points
Toby Emmanuel
Toby Emmanuel
6,782 Points

Thanks guys both have great answers and helped me a lot really appreciate the help!