JavaScript String Object

The String object is used to process existing blocks of characters.

JavaScript strings

A string is used to store a series of characters like "John Doe".

a string can use single or double quotes:

Example

var carname="Volvo XC60";
var carname='Volvo XC60';

you use the position (index) to access any character in the string:

Example

var character=carname[7];

the index of the string is zero-based, so the first character of the string is [0], the second character is [1], and so on.

you can use quotation marks in strings, as follows:

Example

var answer="It's alright";
var answer="He is called 'Johnny'";
var answer='He is called "Johnny"';

or you can use the escape character (\) in a string using quotation marks:

Example

var answer='It\'s alright';
var answer="He is called \"Johnny\"";

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String

String uses the length property length to calculate the length of the string:

Example

var txt="Hello World!";
document.write(txt.length);

var txt="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
document.write(txt.length);

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Find the string in strings

Strings use indexOf() to locate the first occurrence of a specified character in the string:

Example

var str="Hello world, welcome to the universe.";
var n=str.indexOf("welcome");

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if no corresponding character function is found, -1 is returned

The lastIndexOf() method starts at the end of the string to find where the string appears.

Content matching

The match() function is used to find a specific character in a string and, if found, return that character.

Example

var str="Hello world!";
document.write(str.match("world") + "<br>");
document.write(str.match("World") + "<br>");
document.write(str.match("world!"));

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Replace the content

The replace() method replaces some characters with others in the string.

Example

str="Please visit Microsoft!"
var n=str.replace("Microsoft","TutorialFish");

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String case conversion

String case conversion uses the functions toUpperCase() / toLowerCase():

Example

var txt="Hello World!"; // String
var txt1=txt.toUpperCase(); // txt1 text will be converted to uppercase
var txt2=txt.toLowerCase(); // txt2 text will be converted to lower case

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The string is converted to an array

strings are converted to arrays using the split() function:

Example

txt="a,b,c,d,e" // String
txt.split(","); // Use comma to separate
txt.split(" "); // Use spaces to separate
txt.split("|"); // Use vertical bars to separate

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Special characters

In Javascript, you can use backslash (\) to insert special symbols, such as apostrophes, quotation marks, and other special symbols.

Check out the JavaScript code below:

var txt="We are the so-called "Vikings" from the north.";
document.write(txt);

In JavaScript, strings start and stop using single or double quotes. This means that the above string will be cut into: We are the so-called

to solve the above problem, you can use backslash to escape the quotation marks:

var txt="We are the so-called \"Vikings\" from the north.";
document.write(txt);

JavaScript will output the correct text string: We are the so-called "Vikings" from the north.

the following table lists the other special characters that can be escaped using backslashes:

CodeOutput
\'apostrophe
\"double quotation marks
\\diagonal bar
\nline breaks
\renter
\ttab
\bspace
\fpage feeds


String properties and methods

attribute:

  • length

  • prototype

  • constructor

method:

  • charAt()

  • charCodeAt()

  • concat()

  • fromCharCode()

  • indexOf()

  • lastIndexOf()

  • match()

  • replace()

  • search()

  • slice()

  • split()

  • substr()

  • substring()

  • toLowerCase()

  • toUpperCase()

  • valueOf()

For more methods and properties, see JavaScript String Objects