Javascript Method

[javedk]

Please help me understand the code as I don’t know what’s going on.

Method JS

[kevinSmith]

Could you be more specific so we don’t have to go through and explain 30 different things if there is only one thing that is giving you pause?

[javedk]

Hi @kevinSmith
The ele2 is mentioned twice in the block of code. Why is that?

[kevinSmith]

  const ele2 = element.substring(0, 2);
  return ele2 == "hi";

It is a variable holding a string. It is the string of the first two characters of element. It is mentioned twice because it is first declared/initialized and then it is used to make a comparison.

Personally, I think that is a terrible variable name. And one could argue that the variable is unneeded and could have just been:

  return  element.substring(0, 2) == "hi";

That’s kind of sloppy code anyway - the index parameter is never used. I think most modern developers, instead of this:

const arr2 = arr.filter((element, index) => {
  const ele2 = element.substring(0, 2);
  return ele2 == "hi";
});

… would have written this:

const arr2 = arr.filter(element => element.substring(0, 2) === 'hi');

Sometimes you do want to expand things out into extra lines that you don’t need, but I don’t see why that would be necessary here.

[javedk]

Thank you @kevinSmith for the solution. It is now clear.
What you say is absolutely right, that the code is crappy. The source of the code is the book I am currently reading and practicing with. Would you please suggest a good javascript book that would change the way I learn things?
Thank you.

[kevinSmith]

Would you please suggest a good javascript book that would change the way I learn things?

Not off hand. I’d just keep going with what you have. You may pick up some bad habits or idiosyncrasies, but that’s life - you’ll figure that out and fix it. That’s probably true of most methods. Of course, FCC has a course on JS. It’s pretty skimpy so I supplemented it with other books. I used to just go to the library and get a JS book and skim it and if I saw something I didn’t understand, I read that section. In the end, you will be learning from multiple sources so I wouldn’t worry about finding the “perfect” source.