JavaScript String Methods

JavaScript String Methods & Properties

JavaScript string (both primitive and String object) includes a bunch of default properties and methods that can be used for for different purposes.

The global object String is a constructor for strings or a sequence o characters.

String as an object

Everything in JavaScript is an object. For example when a string is created like this:

var myString = 'This is my string for testing';

the variable 'myString' becomes a string object instance. A string object instance has a vast number of properties and methods available to it.

String Methods

Here follows some useful methods that can be used.

charAt() Returns the character at the defined position.
charCodeAt() Returns the Unicode of the character at the defined position.
concat() Concatenate two or more strings, and returns a new concatenated string.
endsWith() Checks if a string ends with the defined string or character.
fromCharCode() Converts the Unicode values to characters.
includes() Checks if a string contains the defined string/character.
indexOf() Returns the first position where the defined value in a string is found.
lastIndexOf() Returns the last position where the defined value in a string is found.
localeCompare() Compares two strings.
match() Search a string with a regular expression, and returns the matches
repeat() Returns a defined number of copies of an existing string.
replace() Search a string for a defined value, or a regular expression. If the value is found return a new string where the specified values is replaced.
search() Search a string for a defined value, or a regular expression. If it's found the position of the match is returned.
slice() Extracts a part of a string and return it as a new string.
split() Split up a string into an array of substrings.
startsWith() Checks if a string starts with the defined character/s
substr() Return the characters from a string, beginning from a defined start position and from that position return the defined number of character.
substring() Return the characters from a string, between two defined posistion.
toLocaleLowerCase() Converts a string to the host's locale lowercase letters.
toLocaleUpperCase() Converts a string to the host's locale uppercase letters.
toLowerCase() Converts a string to lowercase letters.
toString() Returns the value of a String object.
toUpperCase() Converts a string to uppercase letters.
trim() Trim both the start and the end of a string.
valueOf() Returns the primitive value of a String object.

String Properties

Here follows some useful properties that can be used.

constructor Returns the constructor function of a string. 
length Returns the length of a string
prototype Use this to add properties and methods to an object

Learn more about JavaScript Strings

Escape notations

When using special characters they can be encoded using escape notation:

\XXX octal Latin-1 character.
\' single quote
\" double quote
\\ backslash
\n new line
\r carriage return
\v vertical tab
\t tab
\b backspace
\f form feed
\uXXXX unicode codepoint
\u{X} ... \u{XXXXXX} unicode codepoint 
\xXX Latin-1 character

JavaScript is not like all other languages and makes no distinction between single-quoted strings and double-quoted strings. As a consquence of that strings created with either single or double quotes will behave the same.

HTML Wrapper Methods

To have the string wrapped inside a appropriate HTML tag the HTML wrapper methods can be used.

anchor() Is wrapping the string in a <a> tag.
big() Is wrapping the string in a <big> tag.
blink() Is wrapping the string in a <blink> tag.
bold() Is wrapping the string in a <b> tag to make it bold in HTML.
fixed() Is wrapping the string in a <tt> tag.
fontcolor() Is wrapping the string in a  <font color="color"> tag.
fontsize() Is wrapping the string in a <font size="size"> tag.
italics() Is wrapping the string in a <i> tag.
link() Is wrapping the string in a <a>tag where href attribute value is set to specified string.
small() Is wrapping the string in a <small>tag.
strike() Is wrapping the string in a <strike> tag.
sub() Is wrapping the string in a <sub>tag
sup() Is wrapping the string in a <sup>tag

Have in mind that these may not work as expected in all browsers since they are not standard methods.

Learn more about JavaScript Scope

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JavaScript is one of the 3 core language technologies of the World Wide Web that all web developers must learn:

1.      HTML to define the content of web pages.

2.      CSS to specify the layout of web pages.

3.      JavaScript to program the behavior of web pages.

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The benefits of using JavaScript are:

1.      You can validate user input before sending the page off to the server. This saves server traffic, which means less load on your server.

2.      Immediate feedback to the visitors − They don't have to wait for a page reload to see if they have forgotten to enter something.

3.      Increased interactivity − You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.

4.      Richer interfaces − You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.


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