A string (or a text string) is a series of characters. In JavaScript strings variables are declared using two quotes or single quotes.

String literals

You can use quotes inside a string, as long as they don’t match the quotes surrounding the string:

Example:

// Single quote inside double quotes
var answer = "It's alright";          

// Single quotes inside double quotes   
var answer = "He is called 'Johnny'"; 

// Double quotes inside single quotes
var answer = 'He is called "Johnny"';

Join two strings:

The process of joining two strings is also called concatenation. We create a new string using concatenate operator “+”.¬† Below is an example of concatenating two string variables.

 

//create two string variables
var numberOfProducts = "five"
var productType = "potato"

//create a third variable and assign to it a value 
//by concatenating the two string variables we created earlier
var inventory = numberOfProducts + productType

String Methods

String methods can be used using the variable name follow by dot follow by function name.

For example if str=”Hello World” is a sting then we can ues method split like: str.split(” “) and this will create an array of 2 words: [“Hello”,”World”];

Extract a character from string:

There are 2 safe methods for extracting string characters:

  • charAt(position)
  • charCodeAt(position)

Do not use a string like and array str[0]. This is not safe.

 

Some of the string methods:

MethodDescription
charAt()Returns the character at the specified index (position)
charCodeAt()Returns the Unicode of the character at the specified index
concat()Joins two or more strings, and returns a new joined strings
endsWith()Checks whether a string ends with specified string/characters
fromCharCode()Converts Unicode values to characters
includes()Checks whether a string contains the specified string/characters
indexOf()Returns the position of the first found occurrence of a specified value in a string
lastIndexOf()Returns the position of the last found occurrence of a specified value in a string
localeCompare()Compares two strings in the current locale
match()Searches a string for a match against a regular expression, and returns the matches
repeat()Returns a new string with a specified number of copies of an existing string
replace()Searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced
search()Searches a string for a specified value, or regular expression, and returns the position of the match
slice()Extracts a part of a string and returns a new string
split()Splits a string into an array of substrings
startsWith()Checks whether a string begins with specified characters
substr()Extracts the characters from a string, beginning at a specified start position, and through the specified number of character
substring()Extracts the characters from a string, between two specified indices
toLocaleLowerCase()Converts a string to lowercase letters, according to the host’s locale
toLocaleUpperCase()Converts a string to uppercase letters, according to the host’s locale
toLowerCase()Converts a string to lowercase letters
toString()Returns the value of a String object
toUpperCase()Converts a string to uppercase letters
trim()Removes whitespace from both ends of a string

 

To find specification about these functions  go to: W3 String Reference