JavaScript String - Exercises, Practice, Solution
JavaScript String [64 exercises with solution]
[An editor is available at the bottom of the page to write and execute the scripts.]
1. Write a JavaScript function to check whether an `input` is a string or not. Go to the editor
Test Data :
console.log(is_string('w3resource'));
true
console.log(is_string([1, 2, 4, 0]));
false
Click me to see the solution
2. Write a JavaScript function to check whether a string is blank or not. Go to the editor
Test Data :
console.log(is_Blank(''));
console.log(is_Blank('abc'));
true
false
Click me to see the solution
3. Write a JavaScript function to split a string and convert it into an array of words. Go to the editor
Test Data :
console.log(string_to_array("Robin Singh"));
["Robin", "Singh"]
Click me to see the solution
4. Write a JavaScript function to extract a specified number of characters from a string. Go to the editor
Test Data :
console.log(truncate_string("Robin Singh",4));
"Robi"
Click me to see the solution.
5. Write a JavaScript function to convert a string in abbreviated form. Go to the editor
Test Data :
console.log(abbrev_name("Robin Singh"));
"Robin S."
Click me to see the solution.
6. Write a JavaScript function to hide email addresses to protect from unauthorized user. Go to the editor
Test Data :
console.log(protect_email("[email protected]"));
"[email protected]"
Click me to see the solution.
7. Write a JavaScript function to parameterize a string. Go to the editor
Test Data :
console.log(string_parameterize("Robin Singh from USA."));
"robin-singh-from-usa"
Click me to see the solution.
8. Write a JavaScript function to capitalize the first letter of a string. Go to the editor
Test Data :
console.log(capitalize('js string exercises'));
"Js string exercises"
Click me to see the solution.
9. Write a JavaScript function to capitalize the first letter of each word in a string. Go to the editor
Test Data :
console.log(capitalize_Words('js string exercises'));
"Js String Exercises"
Click me to see the solution.
10. Write a JavaScript function that takes a string which has lower and upper case letters as a parameter and converts upper case letters to lower case, and lower case letters to upper case. Go to the editor
Test Data :
console.log(swapcase('AaBbc'));
"aAbBC"
Click me to see the solution.
11. Write a JavaScript function to convert a string into camel case.Go to the editor
Test Data :
console.log(camelize("JavaScript Exercises"));
console.log(camelize("JavaScript exercises"));
console.log(camelize("JavaScriptExercises"));
"JavaScriptExercises"
"JavaScriptExercises"
"JavaScriptExercises"
Click me to see the solution.
12. Write a JavaScript function to uncamelize a string. Go to the editor
Test Data :
console.log(uncamelize('helloWorld'));
console.log(uncamelize('helloWorld','-'));
console.log(uncamelize('helloWorld','_'));
"hello world"
"hello-world"
"hello_world"
Click me to see the solution.
13. Write a JavaScript function to concatenates a given string n times (default is 1). Go to the editor
Test Data :
console.log(repeat('Ha!'));
console.log(repeat('Ha!',2));
console.log(repeat('Ha!',3));
"Ha!"
"Ha!Ha!"
"Ha!Ha!Ha!"
Click me to see the solution.
14. Write a JavaScript function to insert a string within a string at a particular position (default is 1).Go to the editor
Test Data :
console.log(insert('We are doing some exercises.'));
console.log(insert('We are doing some exercises.','JavaScript '));
console.log(insert('We are doing some exercises.','JavaScript ',18));
"We are doing some exercises."
"JavaScript We are doing some exercises."
"We are doing some JavaScript exercises."
Click me to see the solution.
15. Write a JavaScript function to humanized number (Formats a number to a human-readable string.) with the correct suffix such as 1st, 2nd, 3rd or 4th. Go to the editor
Test Data :
console.log(humanize_format());
console.log(humanize_format(1));
console.log(humanize_format(8));
console.log(humanize_format(301));
console.log(humanize_format(402));
"1st"
"8th"
"301st"
"402nd"
Click me to see the solution.
16. Write a JavaScript function to truncates a string if it is longer than the specified number of characters. Truncated strings will end with a translatable ellipsis sequence ("…") (by default) or specified characters. Go to the editor
Test Data :
console.log(text_truncate('We are doing JS string exercises.'))
console.log(text_truncate('We are doing JS string exercises.',19))
console.log(text_truncate('We are doing JS string exercises.',15,'!!'))
"We are doing JS string exercises."
"We are doing JS ..."
"We are doing !!"
Click me to see the solution.
17. Write a JavaScript function to chop a string into chunks of a given length. Go to the editor
Test Data :
console.log(string_chop('w3resource'));
console.log(string_chop('w3resource',2));
console.log(string_chop('w3resource',3));
["w3resource"]
["w3", "re", "so", "ur", "ce"]
["w3r", "eso", "urc", "e"]
Click me to see the solution.
18. Write a JavaScript function to count the occurrence of a substring in a string. Go to the editor
Test Data :
console.log(count("The quick brown fox jumps over the lazy dog", 'the'));
Output :
2
console.log(count("The quick brown fox jumps over the lazy dog", 'fox',false));
Output :
1
Click me to see the solution.
19. Write a JavaScript function to escape a HTML string. Go to the editor
Test Data :
console.log(escape_HTML('<a href="javascript-string-exercise-17.php" target="_blank">'));
Output :
"<a href="javascript-string-exercise-17.php" target="_blank">"
Click me to see the solution.
20. Write a JavaScript function that can pad (left, right) a string to get to a determined length. Go to the editor
Test Data :
console.log(formatted_string('0000',123,'l'));
console.log(formatted_string('00000000',123,''));
Output :
"0123"
"12300000"
Click me to see the solution.
21. Write a JavaScript function to repeat a string a specified times. Go to the editor
Test Data :
console.log(repeat_string('a', 4));
console.log(repeat_string('a'));
Output :
"aaaa"
"Error in string or count."
Click me to see the solution.
22. Write a JavaScript function to get a part of a string after a specified character.Go to the editor
Test Data :
console.log(subStrAfterChars('w3resource: JavaScript Exercises', ':','a'));
console.log(subStrAfterChars('w3resource: JavaScript Exercises', 'E','b'));
Output :
"w3resource"
"xercises"
Click me to see the solution.
23. Write a JavaScript function to strip leading and trailing spaces from a string. Go to the editor
Test Data :
console.log(strip('w3resource '));
console.log(strip(' w3resource'));
console.log(strip(' w3resource '));
Output :
"w3resource"
"w3resource"
"w3resource"
Click me to see the solution.
24. Write a JavaScript function to truncate a string to a certain number of words. Go to the editor
Test Data :
console.log(truncate('The quick brown fox jumps over the lazy dog', 4));
Output :
"The quick brown fox"
Click me to see the solution.
25. Write a JavaScript function to alphabetize a given string. Go to the editor
Alphabetize string : An individual string can be alphabetized. This rearranges the letters so they are sorted A to Z.
Test Data :
console.log(alphabetize_string('United States'));
Output :
"SUadeeinsttt"
Click me to see the solution.
26. Write a JavaScript function to remove the first occurrence of a given 'search string' from a string. Go to the editor
Test Data :
console.log(remove_first_occurrence("The quick brown fox jumps over the lazy dog", 'the'));
Output :
"The quick brown fox jumps over lazy dog"
Click me to see the solution.
27. Write a JavaScript function to convert ASCII to Hexadecimal format. Go to the editor
Test Data :
console.log(ascii_to_hexa('12'));
console.log(ascii_to_hexa('100'));
Output :
"3132"
"313030"
Click me to see the solution.
28. Write a JavaScript function to convert Hexadecimal to ASCII format. Go to the editor
Test Data :
console.log(hex_to_ascii('3132'));
console.log(hex_to_ascii('313030'));
Output :
"12"
"100"
Click me to see the solution.
29. Write a JavaScript function to find a word within a string. Go to the editor
Test Data :
console.log(search_word('The quick brown fox', 'fox'));
console.log(search_word('aa, bb, cc, dd, aa', 'aa'));
Output :
"'fox' was found 1 times."
"'aa' was found 2 times."
Click me to see the solution.
30. Write a JavaScript function check if a string ends with specified suffix. Go to the editor
Test Data :
console.log(string_endsWith('JS PHP PYTHON','PYTHON'));
true
console.log(string_endsWith('JS PHP PYTHON',''));
false
Click me to see the solution.
31. Write a JavaScript function to escapes special characters (&, <, >, ', ") for use in HTML. Go to the editor
Test Data :
console.log(escape_html('PHP & MySQL'));
"PHP & MySQL"
console.log(escape_html('3 > 2'));
"3 > 2"
Click me to see the solution.
32. Write a JavaScript function to remove?non-printable ASCII chars. Go to the editor
Test Data :
console.log(remove_non_ascii('???????PHP-MySQL??????'));
"PHP-MySQL"
Click me to see the solution.
33. Write a JavaScript function to remove non-word characters. Go to the editor
Test Data :
console.log(remove_non_word('PHP [email protected]#$%^&*()+`-={}[]|\\:";\'/?><., MySQL'));
"PHP - MySQL"
Click me to see the solution.
34. Write a JavaScript function to convert a string to title case. Go to the editor
Test Data :
console.log(sentenceCase('PHP exercises. python exercises.'));
"Php Exercises. Python Exercises."
Click me to see the solution.
35. Write a JavaScript function to remove HTML/XML tags from string. Go to the editor
Test Data :
console.log(strip_html_tags('<p><strong><em>PHP Exercises</em></strong></p>'));
"PHP Exercises"
Click me to see the solution.
36. Write a JavaScript function to create a Zerofilled value with optional +, - sign. Go to the editor
Test Data :
console.log(zeroFill(120, 5, '-'));
"+00120"
console.log(zeroFill(29, 4));
"0029"
Click me to see the solution.
37. Write a JavaScript function to test case insensitive (except special Unicode characters) string comparison. Go to the editor
Test Data :
console.log(compare_strings('abcd', 'AbcD'));
true
console.log(compare_strings('ABCD', 'Abce'));
false
Click me to see the solution.
38. Write a JavaScript function to create a case-insensitive search. Go to the editor
Test Data :
console.log(case_insensitive_search('JavaScript Exercises', 'exercises'));
"Matched"
console.log(case_insensitive_search('JavaScript Exercises', 'Exercises'));
"Matched"
console.log(case_insensitive_search('JavaScript Exercises', 'Exercisess'));
"Not Matched"
Click me to see the solution.
39. Write a JavaScript function to Uncapitalize? the first character of a string. Go to the editor
Test Data :
console.log(Uncapitalize('Js string exercises'));
"js string exercises"
Click me to see the solution.
40. Write a JavaScript function to Uncapitalize the first letter of each word of a string. Go to the editor
Test Data :
console.log(unCapitalize_Words('Js String Exercises'));
"js string exercises"
Click me to see the solution.
41. Write a JavaScript function to capitalize each word in the string. Go to the editor
Test Data :
console.log(capitalizeWords('js string exercises'));
"JS STRING EXERCISES"
Click me to see the solution.
42. Write a JavaScript function to uncapitalize each word in the string. Go to the editor
Test Data :
console.log(unCapitalizeWords('JS STRING EXERCISES'));
"js string exercises"
Click me to see the solution.
43. Write a JavaScript function to test whether the character at the provided (character) index is upper case. Go to the editor
Test Data :
console.log(isUpperCaseAt('Js STRING EXERCISES', 1));
false
Click me to see the solution.
44. Write a JavaScript function to test whether the character at the provided (character) index is lower case. Go to the editor
Test Data :
console.log(isLowerCaseAt ('Js STRING EXERCISES', 1));
true
Click me to see the solution.
45. Write a JavaScript function to get humanized number with the correct suffix such as 1st, 2nd, 3rd or 4th. Go to the editor
Test Data :
console.log(humanize(1));
console.log(humanize(20));
console.log(humanize(302));
"1st"
"20th"
"302nd"
Click me to see the solution.
46. Write a JavaScript function to test whether a string starts with a specified string. Go to the editor
Test Data :
console.log(startsWith('js string exercises', 'js'));
true
Click me to see the solution.
47. Write a JavaScript function to test whether a string ends with a specified string. Go to the editor
Test Data :
console.log(endsWith('JS string exercises', 'exercises'));
true
Click me to see the solution.
48. Write a JavaScript function to get the successor of a string. Go to the editor
Note: The successor is calculated by incrementing characters starting from the rightmost alphanumeric (or the rightmost character if there are no alphanumerics) in the
string. Incrementing a digit always results in another digit, and incrementing a letter results in another letter of the same case. If the increment generates a carry, the character to the left of it is incremented. This process repeats until there is no carry, adding an additional character if necessary.
Example :
string.successor("abcd") == "abce"
string.successor("THX1138") == "THX1139"
string.successor("<
string.successor("1999zzz") == "2000aaa"
string.successor("ZZZ9999") == "AAAA0000"
Test Data :
console.log(successor('abcd'));
console.log(successor('3456'));
"abce"
"3457"
Click me to see the solution.
49. Write a JavaScript function to get unique guid (an acronym for 'Globally Unique Identifier?) of the specified length, or 32 by default. Go to the editor
Test Data :
console.log(guid());
console.log(guid(15));
"hRYilcoV7ajokxsYFl1dba41AyE0rUQR"
"b7pwBqrZwqaDrex"
Click me to see the solution.
50. Write a JavaScript program to check if a given string contains alphanumeric characters that are palindromes regardless of special characters and letter case. Go to the editor
A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards, such as the words madam or racecar, the date/time stamps 11/11/11 11:11 and 02/02/2020, and the sentence: "A man, a plan, a canal - Panama". The 19-letter Finnish word saippuakivikauppias (a soapstone vendor), is the longest single-word palindrome in everyday use, while the 12-letter term tattarrattat (from James Joyce in Ulysses) is the longest in English.
Test Data :
('$22_|1372^2731|_22') -> true
('12%^&2') -> false
('234%$$%432') -> true
(1234) -> "It must be string"
('aba%$aba') -> true
('Aba%$aba') -> true
Click me to see the solution.
51. Write a JavaScript function to implement the Boyer-Moore String Search Algorithm. Go to the editor
From Wikipedia,
In computer science, the Boyer-Moore string-search algorithm is an efficient string-searching algorithm that is the standard benchmark for practical string-search literature. It was developed by Robert S. Boyer and J Strother Moore in 1977. The original paper contained static tables for computing the pattern shifts without an explanation of how to produce them. The algorithm for producing the tables was published in a follow-on paper; this paper contained errors which were later corrected by Wojciech Rytter in 1980. The algorithm preprocesses the string being searched for (the pattern), but not the string being searched in (the text). It is thus well-suited for applications in which the pattern is much shorter than the text or where it persists across multiple searches. The Boyer-Moore algorithm uses information gathered during the preprocess step to skip sections of the text, resulting in a lower constant factor than many other string search algorithms. In general, the algorithm runs faster as the pattern length increases. The key features of the algorithm are to match on the tail of the pattern rather than the head, and to skip along the text in jumps of multiple characters rather than searching every single character in the text.
The Boyer-Moore string search algorithm allows linear time in search by skipping indices when searching inside a string for a pattern.
Test Data :
('THIS IS A TEST TEXT', 'TEST') -> 10
('THIS IS A TEST TEXT', 'TEST') -> 14
Click me to see the solution.
52. Write a JavaScript programe to check a given word is exceeding word or not. Go to the editor
There is an increasing gap between two adjacent characters in exceeding words. In ASCII, the gap represents the distance between two characters.
Test Data :
'acgl' -> true
'aebc' -> false
Click me to see the solution.
53. Write a JavaScript function to check a given string is in Flat case or not. Go to the editor
Flat case: As the name implies, flatcase refers to the use of lowercase letters, with no spaces between words.
Test Data :
('j') -> true
('java exercises') -> false
('JavaScriptExercises') -> false
('javascriptexercises') -> true
(12356) -> "It must be a string."
Click me to see the solution.
54. Write a JavaScript function to check a given string is in Kebab case or not. Go to the editor
Kebab case: "the-quick-brown-fox-jumps-over-the-lazy-dog"
Similar to snake case, above, except hyphens rather than underscores are used to replace spaces. It is also known as spinal case, param case, Lisp case in reference to the Lisp programming language, or dash case (or illustratively as kebab-case)
Test Data :
('j') -> true
('java exercises') -> false
('JavaScriptExercises') -> false
('javascriptexercises') -> true
(12356) -> "It must be a string."
Click me to see the solution.
55. Write a JavaScript function to check whether a string is a Pangram or not. Go to the editor
A pangram or holoalphabetic sentence is a sentence using every letter of a given alphabet at least once. Pangrams have been used to display typefaces, test equipment, and develop skills in handwriting, calligraphy, and keyboarding
Test Data :
("The quick brown fox jumps over the lazy dog") -> true
("Waltz, bad nymph, for quick jigs vex.") -> true
("The five boxing wizards jump quickly.") -> true
("The boxing wizards jump quickly.") -> false
(12356) -> "It must be a string."
Click me to see the solution.
56. Write a JavaScript function to check whether a string is in Pascal case or not. Go to the editor
A PascalCase naming convention capitalizes the first letter of each compound word in a variable. It is a best practice in software development to use descriptive variable names.
Test Data :
("XmlStream") -> true
("IOStream") -> true
("javascript") -> false
(12356) -> "It must be a string."
Click me to see the solution.
57. Write a JavaScript function that receives a string and determine whether or not it can be rearranged to become a palindrome. Go to the editor
When a word, phrase, or sequence can be read both forward and backward, it is considered a palindrome. e.g., madam or nurses run.
Test Data :
("maamd") -> true
("civic") -> true
("IO") -> false
(12321) -> "It must be a string."
Click me to see the solution.
58. Write a JavaScript program to find the most frequent character in a given string. Go to the editor
Test Data :
("Madam") -> "a"
("civic") -> "c"
("HellloL223LLL") -> "L"
(12321) -> "It must be a string."
Click me to see the solution.
59. Write a JavaScript program to find the most frequent word in a given string. Go to the editor
Test Data :
("The quick brown fox jumps over the lazy dog") -> "the"
("Python is a high-level, general-purpose programming language.") -> "python"
(" It was the same man, she was sure of it. It's always the same, Chauncey.") -> "was"
(12321) -> "It must be a string."
Click me to see the solution.
60. Write a JavaScript function to reverse words in a given string. Go to the editor
Test Data :
("abc") -> "cba"
("JavaScript Exercises") -> "tpircSavaJ sesicrexE"
(1234) -> "It must be a string."
Click me to see the solution.
61. Write a JavaScript function to find the length of longest subsequence present in given two sequences. Go to the editor
It is important to understand that a subsequence is a sequence that appears in a similar relative order, but is not necessarily contiguous.
Test Data :
("abcda", "abcdef") -> 4
("ABCD", "ACBAD") -> 3
("pqr", "pqr") -> 3
("pqr", "abc") -> 0
Click me to see the solution.
62. Write a JavaScript function to get the length of the longest valid parentheses (well-formed) from a given string containing just the characters '[' and ']'. Go to the editor
Test Data :
The longest valid parentheses substring is "[]".
("[[]") -> 2
The longest valid parentheses substring is "[][]".
("][][]]") -> 4
No valid parentheses substring.
("") -> 0
Click me to see the solution.
63. Write a JavaScript function to find the length of the longest palindromic subsequence in a given string. Go to the editor
Subsequences are sequences that can be created by deleting some or all of the elements from another sequence without changing their order.
Test Data :
("aaaba") -> 4
("maadaem") -> 5
("zkksk") -> 3
("ab") -> 1
("") -> ""
Click me to see the solution.
64. Write a JavaScript function that takes a positive integer and reverse the binary representation of that integer. Finally return the decimal version of the binary string. Go to the editor
Test Data :
(100) -> 19
Explanation:
Binary representation of 100 is 1100100
Reverse of 1100100 is 10011
Decimal form of 10011 is 19
(1134) -> 945
Explanation:
Binary representation of 1134 is 10001101110
Reverse of 10001101110 is 1110110001
Decimal form of 1110110001 is 945
Click me to see the solution.
More to Come !
* To run the code mouse over on Result panel and click on 'RERUN' button.*
Live Demo:
See the Pen javascript-common-editor by w3resource (@w3resource) on CodePen.
Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.
JavaScript: Tips of the Day
Returns the difference between two arrays, after applying the provided function to each array element of both
Example:
const tips_differenceBy = (x, y, fn) => {
const s = new Set(y.map(fn));
return x.map(fn).filter(el => !s.has(el));
};
console.log(tips_differenceBy([3.1, 1.5], [3.3, 3.8], Math.floor));
console.log(tips_differenceBy([{ x: 3 }, { x: 2 }], [{ x: 2 }], v => v.x));
Output:
[1] [3]
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