JavaScript: Check whether a given array of integers represents either a strictly increasing or a strictly decreasing sequence
JavaScript Basic: Exercise-122 with Solution
Write a JavaScript program to check whether a given array of integers represents either a strictly increasing or a strictly decreasing sequence.
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 array of integers represents either a strictly increasing or a strictly decreasing sequence</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function is_monotonous(num) {
if (num.length === 1) {
return true;
}
var num_direction = num[1] - num[0];
for (var i = 0; i < num.length - 1; i++) {
if (num_direction * (num[i + 1] - num[i]) <= 0) {
return false;
}
}
return true;
}
console.log(is_monotonous([1, 2, 3]));
console.log(is_monotonous([1, 2, 2]))
console.log(is_monotonous([-3, -2, -1]))
Sample Output:
true false true
Flowchart:

ES6 Version:
function is_monotonous(num) {
if (num.length === 1) {
return true;
}
const num_direction = num[1] - num[0];
for (let i = 0; i < num.length - 1; i++) {
if (num_direction * (num[i + 1] - num[i]) <= 0) {
return false;
}
}
return true;
}
console.log(is_monotonous([1, 2, 3]));
console.log(is_monotonous([1, 2, 2]))
console.log(is_monotonous([-3, -2, -1]))
Live Demo:
See the Pen javascript-basic-exercise-122 by w3resource (@w3resource) on CodePen.
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Previous: Write a JavaScript program to check if a given matrix is lower triangular or not.
Next: Write a JavaScript program to find if the members of an given array of integers is a permutation of numbers from 1 to a given integer.
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JavaScript: Tips of the Day
Returns the sum of the powers of all the numbers from start to end (both inclusive)
Example:
const sumPower = (end, power = 2, start = 1) => Array(end + 1 - start) .fill(0) .map((x, i) => (i + start) ** power) .reduce((a, b) => a + b, 0); console.log(sumPower(10)); // 385 console.log(sumPower(10, 3)); // 3025 console.log(sumPower(10, 3, 5)); // 2925
Output:
385 3025 2925
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