JavaScript: Test whether a given array of integers contains 30 or 40 twice

JavaScript Basic: Exercise-79 with Solution

Check if Array Contains 30 and 40 Twice

Write a JavaScript program to test whether a given array of integers contains 30 or 40 twice. The array length should be 0, 1, or 2.

Visual Presentation:

Sample Solution:

JavaScript Code:

// Function to check if the first two elements of an array are either both 30 or both 40
function twice3040(arra1) {
    let a = arra1[0], // Extract the first element
        b = arra1[1]; // Extract the second element
    return (a === 30 && b === 30) || (a === 40 && b === 40); // Check if both are 30 or both are 40
}	

// Example usage
console.log(twice3040([30, 30])); // Should return true
console.log(twice3040([40, 40])); // Should return true
console.log(twice3040([20, 20])); // Should return false
console.log(twice3040([30])); // Should return false

Output:

true
true
false
false

Live Demo:

See the Pen JavaScript - Test whether an array of integers of length 2 does not contain 1 or a 3-basic-ex-78 by w3resource (@w3resource) on CodePen.

Flowchart:

ES6 Version:

// ES6 version using destructuring assignment and arrow function
const twice3040 = ([a, b]) => (a === 30 && b === 30) || (a === 40 && b === 40);

// Example usage
console.log(twice3040([30, 30]));
console.log(twice3040([40, 40]));
console.log(twice3040([20, 20]));
console.log(twice3040([30]));

For more Practice: Solve these Related Problems:

• Write a JavaScript program that checks if an array contains the numbers 30 and 40 exactly twice each, regardless of order.
• Write a JavaScript function that counts occurrences of 30 and 40 in an array and returns true if both appear exactly two times.
• Write a JavaScript program that validates an array by ensuring that the numbers 30 and 40 each occur twice, handling arrays of varying lengths.
• Write a JavaScript function that uses a frequency map to verify that both 30 and 40 have a count of 2 in the array.

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