Strings in JavaScript

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In this video we will discuss different functions that are available to manipulate strings in JavaScript.



A string is any text inside quotes. You can use either single or double quotes.

var string1 = "string in double quotes"

var string2 = 'string in single quotes'

Concatenating strings : There are 2 options to concatenate strings in JavaScript. You could either use + operator or concat() method

Example : Concatenating strings using + operator

var string1 = "Hello"

var string2 = "JavaScript"

var result = string1 + " " + string2;

alert(result);

Output : Hello JavaScript

Example : Concatenating strings using concat() method

var string1 = "Hello"

var string2 = "JavaScript"

var result = string1.concat(" ", string2);

alert(result);

Output : Hello JavaScript

If you want single quotes inside a string, there are 2 options
Option 1 : Place your entire string in double quotes, and use single quotes inside the string wherever you need them.

Example : 

var myString = "Welcome to 'JavaScript' Training";

alert(myString);

Output : Welcome to 'JavaScript' Training

Option 2 : If you prefer to place your entire string in single quotes, then use escape sequence character \ with a single quote inside the string.

Example : 

var myString = 'Welcome to \'JavaScript\' Training';

alert(myString);

Output : Welcome to 'JavaScript' Training

Please Note : You can use the above 2 ways if you need double quotes inside a string

Converting a string to uppercase : Use toUpperCase() method

Example :

var upperCaseString = "JavaScript";

alert(upperCaseString.toUpperCase());

Output : JAVASCRIPT

Converting a string to lowercase : Use toLowerCase() method

Example :

var lowerCaseString = "JavaScript";

alert(lowerCaseString.toLowerCase());

Output : javascript

Length of string javascript : Use length property

Example : alert("JavaScript".length);

Output : 10

Example :

var myString = "Hello JavaScript";

alert(myString.length);

Output : 16

Remove whitespace from both ends of a string : Use trim() method

Example :

var string1 = " AB ";

var string2 = " CD ";

var result = string1.trim() + string2.trim();

alert(result);

Output : ABCD

Replacing strings in javascript : Use replace() method. This method searches a given string for a specified value or a regular expression, replaces the specified values with the replacement values and returns a new string. This method does not change the original string.

Example : Replaces JavaScript with World

var myString = "Hello JavaScript";

var result = myString.replace("JavaScript", "World");

alert(result);

Output : Hello World

Example : Perform a case-sensitive global replacement. In this example, we are using a regular expression between the 2 forward slashes(//). The letter g after the forward slash specifies a global replacement. The match here is case sensitive. This means Blue(with capital B) is not replaced with green.

var myString = "A Blue bottle with a blue liquid is on a blue table";

var result = myString.replace(/blue/g, "green");

alert(result);

Output : A Blue bottle with a green liquid is on a green table

Example : Perform a case-insensitive global replacement. The letters gi after the forward slash indicates to do global case-insensitive replacement. Notice that the word Blue(with capital B) is also replaced with green.

var myString = "A Blue bottle with a blue liquid is on a blue table";

var result = myString.replace(/blue/gi, "green");

alert(result);

Output : A green bottle with a green liquid is on a green table