JavaScript: Check whether a given string contains only Latin letters and no two uppercase and no two lowercase letters are in adjacent positions
JavaScript Basic: Exercise-101 with Solution
Write a JavaScript program to check whether a given string contains only Latin letters and no two uppercase and no two lowercase letters are in adjacent positions.
Pictorial Presentation:

Sample Solution:
HTML Code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title> Check whether a given string contains only Latin letters and no two uppercase and no two lowercase letters are in adjacent positions</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function test_string(input_str) {
var is_lower_case = function(symbol) {
if ('a' <= symbol && symbol <= 'z') {
return true;
}
return false;
}
var is_upper_case = function(symbol) {
if ('A' <= symbol && symbol <= 'Z') {
return true;
}
return false;
}
var is_first_char_lower = is_lower_case(input_str[0]),
is_first_char_upper = is_upper_case(input_str[0]);
if (!(is_first_char_lower || is_first_char_upper)) {
return false;
}
for (var i = 1; i < input_str.length; i++) {
if (i % 2) {
if (is_lower_case(input_str[i]) === is_first_char_lower ||
is_upper_case(input_str[i]) === is_first_char_upper) {
return false;
}
} else {
if (is_lower_case(input_str[i]) !== is_first_char_lower ||
is_upper_case(input_str[i]) !== is_first_char_upper) {
return false;
}
}
}
return true;
}
console.log(test_string('xYr'));
console.log(test_string('XXyx'));
Sample Output:
true false
Flowchart:

ES6 Version:
function test_string(input_str) {
const is_lower_case = symbol => {
if ('a' <= symbol && symbol <= 'z') {
return true;
}
return false;
};
const is_upper_case = symbol => {
if ('A' <= symbol && symbol <= 'Z') {
return true;
}
return false;
};
const is_first_char_lower = is_lower_case(input_str[0]);
const is_first_char_upper = is_upper_case(input_str[0]);
if (!(is_first_char_lower || is_first_char_upper)) {
return false;
}
for (let i = 1; i < input_str.length; i++) {
if (i % 2) {
if (is_lower_case(input_str[i]) === is_first_char_lower ||
is_upper_case(input_str[i]) === is_first_char_upper) {
return false;
}
} else {
if (is_lower_case(input_str[i]) !== is_first_char_lower ||
is_upper_case(input_str[i]) !== is_first_char_upper) {
return false;
}
}
}
return true;
}
console.log(test_string('xYr'));
console.log(test_string('XXyx'));
Live Demo:
See the Pen javascript-basic-exercise-101 by w3resource (@w3resource) on CodePen.
Contribute your code and comments through Disqus.
Previous: Write a JavaScript program to check if there is at least one element which occurs in two given sorted arrays of integers.
Next: Write a JavaScript program to find the number of inversions of a given array of integers.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
JavaScript: Tips of the Day
Converts a string to title case
Example:
const toTitleCase = str => str .match(/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g) .map(x => x.charAt(0).toUpperCase() + x.slice(1)) .join(' '); console.log(toTitleCase('some_database_field_name')); // 'Some Database Field Name' console.log(toTitleCase('Some label that needs to be title-cased')); // 'Some Label That Needs To Be Title Cased' console.log(toTitleCase('some-package-name')); // 'Some Package Name' console.log(toTitleCase('some-mixed_string with spaces_underscores-and-hyphens')); // 'Some Mixed String With Spaces Underscores And Hyphens'
Output:
"Some Database Field Name" "Some Label That Needs To Be Title Cased" "Some Package Name" "Some Mixed String With Spaces Underscores And Hyphens"
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework