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JavaScript: strings

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:

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.

 

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