JavaScript String Object with Example

Updated on     Kisan Patel

A JavaScript string can be both a primitive data type or an object. As a primitive type, it joins with four other JavaScript primitive types: number, Boolean (true or false), null (no value), and undefined (unknown).

A string is zero or more characters delimited by quotes, either single quotes.

‘This is a string’

Or double quotes.

“This is a string”

A string object is called String.

A String object can be instantiated using the JavaScript new operator, to create a new object instance.

var name = new String("Kisan Patel");

Once instantiated, any one of the available string properties can be accessed on it, such as in the following code, where the string is lowercased using the String object method toLowerCase.

var newName = name.toLowerCase(); // new string is now kisan patel

If you access the String constructor without using new, you will create a string literal rather than a String object.

var name = String("Kisan Patel");

String Object Methods

Method Description
charAt() Returns the character at the specified index
charCodeAt() Returns the Unicode of the character at the specified index
concat() Joins two or more strings, and returns a copy of the joined strings
fromCharCode() Converts Unicode values to 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
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
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
valueOf() Returns the primitive value of a String object

JavaScript

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