String Methods

.length()

Description of what method does:

returns the number of characters that the string contains.

When to use:

when you want to find the number of characters that the string contains

Example 1:

const str = 'this string has 29 characters'
console.log(str.length) // 29

.trim()

Description of what method does:

removes white spaces from the beginning and end of a string

When to use:

when processing the string of a user input field. It is easy to accidentally add spaces, and this ensures you handle the relevant characters.

Syntax:

Example 1:

const str = '     the secret to life is 42         '
console.log(str.trim()) // "the secret to life is 42"

Example 2:

Example 3:

.includes()

Description of what method does:

determines if a substring is contained in a larger string and returns true or false

When to use:

string matching for searching/parsing

Syntax:

Example 1:

const author = 'George Orwell'
const userSearchTerm1 = 'George'
const userSearchTerm2 = 'Douglas'

console.log(author.includes(userSearchTerm1)) // true
console.log(author.includes(userSearchTerm2)) // false

Example 2:

Example 3:

.indexOf()

Description of what method does:

returns the index of the substring within the string. If the substring is not contained in the original string, it will return -1.

When to use:

when you want to find the index of a substring

Syntax:

Example 1:

const author = 'George Orwell'
const userSearchTerm1 = 'Orwell'
const userSearchTerm2 = 'Douglas'

console.log(author.indexOf(userSearchTerm1)) // 7 

console.log(author.indexOf(userSearchTerm2)) // -1

Example 2:

Example 3:

.toUpperCase()

Description of what method does:

returns a string with all upper case letters

When to use:

when you want to capitalize all the letters in a string

Syntax:

Example 1:

const str = 'We are some small letters that want to be big'
console.log(str.toUpperCase()) // 'WE ARE SOME SMALL LETTERS THAT WANT TO BE BIG"

Example 2:

Example 3:

.toLowerCase()

Description of what method does:

returns a string with all lower case letters

When to use:

when you want to return all the letters of a string to lowercase

Syntax:

Example 1:

const str = 'This has BIG LETTERS. They want to all be small.'
console.log(str.toLowerCase()) // 'this has big letters. they all want to all be small.'

Example 2:

Example 3:

.replace()

Description of what method does:

returns a string with a pattern replaced by a replacement string. It takes either a regex or a string as the pattern. With a regex you can globally replace all matches (using the g option), but with a string it will only replace the first occurrence. In the example below, you will notice that world is replaced only once in the first call since it uses a string pattern.

When to use:

When you want to replace a string with a new value

Syntax:

Example 1:

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Example 3:

.slice()

Description of what method does:

extracts a section of a string based on the index supplied and return it as a new string.

When to use:

when you know the structure of a sting and want to retrieve a certain portion

Syntax:

Example 1:

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Example 3:

.split()

Description of what method does:

takes a separator which you want to split apart the string on, and it returns an array of strings

When to use:

when you know your string uses a certain character to separate data, or if you want to operate on specific substrings individually.

Syntax:

Example 1:

Example 2:

Example 3:

.repeat()

Description of what method does:

returns a string consisting of the elements of the object repeated the given number of times.

When to use:

when you want to repeat a string

Syntax:

Example 1:

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Example 3:

.match()

Description of what method does:

retrieves the matches when matching a string against a regular expression

When to use it:

when you want to return an array of matching strings

Syntax:

Example 1:

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Example 3:

.charAt()

Description of what method does:

returns the string character at a given index.

When to use:

When you want to find a character at a given index

Syntax:

Example 1:

Example 2:

Example 3:

.charCodeAt()

Description of what method does:

returns the unicode of the character at a specified index in a string. This an UTF-16 cone integer between 0 and 65535.