String Indexing

We sometimes need to access individual characters in a string. The characters in a string can be located using their index value, which represents their position in the string. Enclosing the index in square brackets will select a single character from a string:

string[index number]

Characters are indexed from left to right, starting from the position 0, not 1! Blank spaces are also counted as characters.

let str = "Hello";
console.log(str[0]);                  // H
console.log(str[2]);                  // l

Note that strings are immutable, we can not change any character in a string, but we can create new strings.

The slice() Method

To get a substring, use: str.slice()

slice(start, end) extracts a part of a string and returns a new string including the part of the string from index start to index end (excluding end).

If there is only one argument like in slice(start), then slice goes till the end of the string.

let food ='blueberry muffin';

let n = food.slice(4,9);
console.log(n);         // berry (slice from index 4 to 9, excluding 9)

let r = food.slice(4);
console.log(r);         // berry muffin (slice from index 4 to the end)

To understand how slicing works, think of an index as a pointer between characters in a string:

 +---+---+---+---+---+---+---+---+---+---+
 | J | a | v | a | S | c | r | i | p | t |
 +---+---+---+---+---+---+---+---+---+---+
 0   1   2   3   4   5   6   7   8   9   10

0 is before the first element, slice(start, end) includes everything between the two indices.