Strings

Searching

indexOf(): Returns the first index of a value (-1 if not found).
js
```
"hello".indexOf("l") // 2
```
lastIndexOf(): Returns the last index of a value (-1 if not found).
js
```
"hello".lastIndexOf("l") // 3
```
includes(): Returns true or false if a value exists.
js
```
"hello".includes("ell") // true
```
startsWith(): Checks whether the string starts with a value.
js
```
"hello".startsWith("he") // true
```
endsWith(): Checks whether the string ends with a value.
js
```
"hello".endsWith("lo") // true
```
search(): Searches using a regex and returns an index.
js
```
"hello".search(/l/) // 2
```

slice(start, end): Extracts part of a string and supports negative indexes.
js
```
"hello".slice(1, 3) // el
```
substring(start, end): Like slice, but does not support negative indexes; a negative index is treated as 0.
js
```
"hello".substring(1, 3) // el
```
at(index): Returns the character at an index, supports negative indexes, and returns undefined if the index is out of range.
js
```
"hello".at(-1) // o
```
charAt(index): Returns the character at an index and an empty string if the index is out of range.
js
```
"hello".charAt(0) // h
```
charCodeAt(index): Returns a UTF-16 character code and returns NaN if the index is out of range.
js
```
"A".charCodeAt(0) // 65
```

toUpperCase(): Converts to uppercase.
js
```
"hello".toUpperCase() // 'HELLO'
```
toLowerCase(): Converts to lowercase.
js
```
"HELLO".toLowerCase() // 'hello'
```
trim(): Removes whitespace from both ends.
js
```
"  hi  ".trim() // 'hi'
```
trimStart(): Removes leading whitespace.
js
```
"  hi  ".trimStart() // 'hi  '
```
trimEnd(): Removes trailing whitespace.
js
```
"  hi  ".trimEnd() // '  hi'
```
replace(a, b): Replaces the first match.
js
```
"aabbaa".replace("a", "x") // "xabbaa"
```

replaceAll(a, b): Replaces all matches.

"aabbaa".replaceAll("a", "x") // "xxbbxx"

repeat(n): Repeats a string n times.
js
```
"ab".repeat(3) // "ababab"
```
padStart(len, char): Pads from the start.
js
```
"5".padStart(3, "0") // "005"
```
padEnd(len, char): Pads from the end.
js
```
"5".padEnd(3, "0") // "500"
```

split(): Splits a string.

"a,b,c".split("") // ["a", "b", "c"]
"hello".split("") // ["h", "e", "l", "l", "o"]
"hello".split("", 2) // ["h", "e"]

String(123) // "123"
(123).toString() // "123"
(255).toString(16) // "ff"
String.fromCharCode(65) // "A"