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JavaScript: Find whether the members of a given array of integers is a permutation of numbers from 1 to a given integer

JavaScript Basic: Exercise-123 with Solution

Write a JavaScript program to find whether the members of a given array of integers is a permutation of numbers from 1 to a given integer.

Pictorial Presentation:

JavaScript: Find whether the members of a given array of integers is a permutation of numbers from 1 to a given integer.

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title> Find whether the members of a given array of integers is a permutation of numbers from 1 to a given integer</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function is_permutation(input_arr, n) {
    for (var i = 0; i < n; i++) {
        if (input_arr.indexOf(i + 1) < 0) 
          return false;
    }
    return true;
}
console.log(is_permutation([1, 2, 3, 4, 5], 5));
console.log(is_permutation([1, 2, 3, 5], 5));

Sample Output:

true
false

Flowchart:

Flowchart: JavaScript - Find whether the members of a given array of integers is a permutation of numbers from 1 to a given integer

ES6 Version:

function is_permutation(input_arr, n) {
    for (let i = 0; i < n; i++) {
        if (!input_arr.includes(i + 1)) 
          return false;
    }
    return true;
}
console.log(is_permutation([1, 2, 3, 4, 5], 5));
console.log(is_permutation([1, 2, 3, 5], 5));

Live Demo:

See the Pen javascript-basic-exercise-123 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to check whether a given array of integers represents either a strictly increasing or a strictly decreasing sequence.
Next: Write a JavaScript program to create the value of NOR of two given booleans.

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JavaScript: Tips of the Day

Parameter's value

function getItems(fruitList, ...args, favoriteFruit) {
  return [...fruitList, ...args, favoriteFruit]
}

getItems(["banana", "apple"], "pear", "orange")

...args is a rest parameter. The rest parameter's value is an array containing all remaining arguments, and can only be the last parameter! In this example, the rest parameter was the second parameter. This is not possible, and will throw a syntax error.

function getItems(fruitList, favoriteFruit, ...args) {
  return [...fruitList, ...args, favoriteFruit];
}


getItems(['banana', 'apple'], 'pear', 'orange');
The above example works. This returns the array [ 'banana', 'apple', 'orange', 'pear' ].

Ref: https://bit.ly/3jFRBje