abc-notepedia

# Strings

# Properties & Methods (opens new window)

# .length (opens new window)

property - contains the length of the string, in UTF-16 code units

  • to get the last letter of a string, you can subtract one from the string's length. var lastLetter = firstName[firstName.length - 1];

# square bracket notation []

return any character inside a string

  • But string values are immutable: str[0]="x" doesn't work

# indexOf() (opens new window)

checks if a substring is present inside a string

  • If the substring is found inside the main string, it returns a number representing the index position of the substring
  • If the substring is not found inside the main string, it returns a value of -1.
if(browserType.indexOf('mozilla') === -1) {
  // do stuff with the string if the 'mozilla'
  // substring is NOT contained within it
}

# .lastIndexOf() (opens new window)

# slice() (opens new window)

extracts a section of a string and returns it as a new string, without modifying the original string.

  • the first parameter is the character position to start extracting at, and the second parameter is the character position after the last one to be extracted.
  • to extract all of the remaining characters in a string after a certain character, don't include the second parameter!
  • slice(x,y) slice (start-end)
  • slice(-4) last 4 letters

# toLowerCase() (opens new window) - toUpperCase() (opens new window)

convert all the characters to lower- or uppercase

# replace() (opens new window)

replace one substring inside a string with another substring.

  • two parameters — the string you want to replace, and the string you want to replace it with.
  • doesn't change the string

# .split() (opens new window)

divides a String into an array

  • let digits = number.toString().split(''); converts number into an array of strings for each digit

# .repeat() (opens new window)

returns a new string which contains the specified number of copies of the string on which it was called

# .trim() (opens new window)

# .trimStart() (opens new window) - .trimEnd() (opens new window)

# .substring() (opens new window)

# .substr() (opens new window)

# .replaceAll() (opens new window)

# .endsWith() (opens new window)

# .concat() (opens new window)

# .includes() (opens new window)

# Number to String

let str = `${number}`

let str = number + ""

let str = String(number)

# String Concatenation

let name = 'John'
let age = '32'

console.log ("Hello, my name is " + name + " and I am " + age + " years old")

let firstName = 'John';
let lastName = 'Doe'

let fullName = firstName + ' ' + lastName

console.log (fullName);

# Template Literals

template literals use backticks ` and ${} to interpolate values into a string

in template literals ${..}is called codeblock

const myPet = 'cat';
console.log(`I have a ${myPet}.`);
// Output: I have a cat.

# Strings - Escape Character \

  • \n - Newline
  • \' - Single quote
  • \" - Double quote
  • \\ - Backslash
  • \t - Horizontal Tab
  • \v - Vertical Tab
  • \0 - Nul char

← Arrays →