Javascript Course


List with useful JavaScript methods for String, and functions to work with strings in JS scripts.

str.concat(s1, s2, ..) - joins the string 'str' with the substrings 's1, s2, ..' and returns a new string..
let str ='Hello, ';
let str2 = str.concat('CoursesWeb', '.net');
document.write(str2);
str.includes(s2) - returns True if the substring s2 is in 'str', otherwise returns False.
- This method is case-sensitive (makes difference between uppercase and lowercase letters).
let str ='Life is Happiness, Be Happy.';
if(str.includes('Happ')) document.write('The string contains: Happ');
str.endsWith(s2) - returns True if the string 'str' ends with substring 's2', otherwise False. It is case-sensitive.
let str ='JavaScript string.';
if(str.endsWith('ing.')) document.write('The string ends with: ing.');
str.indexOf(s2) - returns the position of the first occurrence of the substring 's2' in 'str', or -1, if the substring is not found.
let str ='JS example string.';
var ix = str.indexOf('example');
if(ix !=-1) document.write('The word "example" starts from index: '+ ix);
str.match(RegExp) - Compares a regular expression and a string to see if they match. Returns an array with the matches or 'null'.
const email ='some_name@domain.net';

//is_em is an array like: ['email', 'name', 'domain'] or null
var is_em = email.match(/^([A-z0-9]+[A-z0-9._%-]*)@([A-z0-9_\-\.]+\.[A-z]{2,5})$/i);

//if email is a valid address writes the name
if(is_em){
 document.write('The name from the address: "'+email+'" is: '+ is_em[1]);
}
str.repeat(nr) - returns a string consisting of the copies of the string 'str' repeated the given 'nr' times.
let str ='abc';
let str2 = str.repeat(2);
document.write(str2); // abcabc
str.replace(s0, s2) - replaces in 'str' the matched substring 's0' with the value from 's2'.
let str ='Visit: https://marplo.net';
let str2 = str.replace('marplo.net', 'gamv.eu');
document.write(str2); // Visit: https://gamv.eu
str.search(RegExp) - executes the search for a match between a regular expression and a specified string. Returns the position of the match, or -1 if no match is found.
let str ='The Peace is peaceful';
var ix = str.search(/peace/i);
document.write(ix); // 4
str.slice(start, end) - pulls out a specified section of a string (between start index and the end index) and returns a new string, or -1.
let str ='Tutorials JS';
document.write(str.slice(0, 5)); //Tutor
str.split(separator, limit) - separates a string into an array of strings based on a separator sent as a parameter to the method. Limit is optional (an integer that specifies the number of splits).
let str ='How are you?';
var ar_str = str.split(' '); //['How', 'are', 'you?']
document.write(ar_str[1]); // are
str.startsWith(s2) - returns True if 'str' starts with 's2', otherwise False. Is case-sensitive.
let str ='Simple JavaScript string.';
if(str.startsWith('Simp')) document.write('The string starts with: Sim');
str.substr(start, length) - returns a portion of the string specified with a starting position and through the specified number of character (length).
var str ='JS Tutorials';
document.write(str.substr(3, 5)); // Tutor
str.substring(start, end) - extracts the characters from a string, between two specified indices (not including "end" itself), and returns the sub-string.
let str ='Hi everyone';
document.write(str.substring(3, 7)); // ever
str.toLowerCase() - returns the string to lowercase letters.
let str = 'I love Peace';
document.write(str.toLowerCase()); // i love peace
str.toUpperCase() - returns the string to all uppercase letters.
let str ='I love Peace';
document.write(str.toUpperCase()); //I LOVE PEACE
str.trim() - trims whitespace from the beginning and end of the string.
let str =' Hello to Me. ';
document.write('<pre>'+ str +' (without trim)</pre>');
document.write('<pre>'+ str.trim() +' (with trim)</pre>');

Aditional to this method are: trimStart() and trimEnd(). To trim whitespace from beginning or from the end.

str.toFixed(n) - formatting a number as a numeric string to a value rounded to 'n' decimals.
let nr =78.468;
document.write(nr.toFixed(2)); // 78.47

- You can find a list with the methods of the String object at MDN: String JavaScript.


Global functions for strings

escape(string) - converts most special characters to hexadecimal character codes (except: '@ * _ + - . /').
let str ='Be&Well @!';
document.write(escape(str)); // Be&Well @!
unescape(string) - performs the reverse operation of the escape() function.
let str ='Be&Well @! ';
document.write(unescape(str)); // Be&Well @!
encodeURIComponent(string) - encodes characters that separate different components of a URL (except letters, digits, and the following characters: - _ . ! ~ * ` ( ) ).
So you can safely encode a string for use as a single component. This is most commonly used for encoding a string for use as a query string value or parameter.
let str ='https://coursesweb.net/?x=abc';
document.write(encodeURIComponent(str)); // https://coursesweb.net/?x=abc
decodeURIComponent(string) - performs the reverse operation of the encodeURIComponent() function.
let str ='https://coursesweb.net/?x=abc';
document.write(decodeURIComponent(str)); // https://coursesweb.net/?x=abc

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which tag create a highlighted bolded text?
<q> <strong> <em>
<p>Address: <strong>http://CoursesWeb.net/</strong> - Tutorials.</p>
Which of these CSS codes displays the text bolded?
text-size: 18px; font-style: italic; font-weight: 800;
#id {
  font-weight: 800;
}
What JavaScript function can be used to call another function multiple times, to a specified time interval?
setInterval() setTimeout() push()
function someFunction() { alert("CoursesWeb.net"); }
setInterval("someFunction()", 2000);
Click on the correctly defined variable in PHP.
var vname = 8; $vname = 8; $vname == 8;
$vname = 8;
echo $vname;
Methods of the String object in JS

Last accessed pages

  1. Responses (284)
  2. Detecting events in ActionScript 3 (1303)
  3. Diamond shape with CSS (4032)
  4. Ajax script to Save Canvas Image on Server (6723)
  5. Convert BBCode to HTML and HTML to BBCode with JavaScript (8981)

Popular pages this month

  1. Courses Web: PHP-MySQL JavaScript Node.js Ajax HTML CSS (384)
  2. SHA1 Encrypt data in JavaScript (292)
  3. PHP Unzipper - Extract Zip, Rar Archives (276)
  4. SHA256 Encrypt hash in JavaScript (264)
  5. Read Excel file data in PHP - PhpExcelReader (245)