String Indexing

Imagine you have my name, Jeremy, and you want to get my initial J out of that. How would we go about doing it?

Well, you can think of a string as being a series of letters. So "Jeremy" has six letters, J-E-R-E-M-Y, and each one has a position. "J" is in the first position, "y" is in the last position.

Now, in JavaScript and most programming languages, these positions start at zero. So the first letter "J" is at position zero, and then next we have "e", which is at position one, "r" at two, "e" at three, "m" at four, and "y" at five.

Now, this starting with zero thing is pretty weird, and honestly, life would be easier if we just started counting from one, like in the normal world.

But we don't. In most programming languages, we start counting from zero instead, so you just need to learn that.

So if we want to get a letter at a specific position, we can use square brackets with the number inside.

So if we say "Jeremy"[0], we're saying give me the first letter of the word "Jeremy".

If we say "Jeremy"[1], we're saying give me the second letter.

"Jeremy"[0]
"Jeremy"[1]

And we can do this with variables too. So if we make a variable called name and set its value to the string "Jeremy", then we can do name[0], and we'll get "J" again.

let name = "Jeremy"
name[0]

One thing to be clear on, what you get back from name[0] is just another string. It's another piece of paper with J on it. There's nothing special about it. It's a string just like "Jeremy" is a string.

It just happens to have one letter on it instead of six.

And doing this doesn't affect the original string at all. We're not, like, ripping the J off or anything. We're just finding which of the letters we want, and then making a new string with that in.