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

JavaScript Basic: Exercise-79 with Solution

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.

Pictorial Presentation:

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

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JavaScript program to test whether a given array of integers contains 30 or 40 twice. The array length should be 0, 1, or 2.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function twice3040(arra1) {
    let a = arra1[0],
        b = arra1[1];
    return (a === 30 && b === 30) || (a === 40 && b === 40);
}

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

Sample Output:

true
true
false
true

Flowchart:

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

ES6 Version:

function twice3040(arra1) {
    let a = arra1[0];
    let b = arra1[1];
    return (a === 30 && b === 30) || (a === 40 && b === 40);
}

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

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.


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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04