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JavaScript: Get the first element of an array

JavaScript Array: Exercise-1 with Solution

Write a JavaScript function to check whether an 'input' is an array or not.

Test Data:
console.log(is_array('w3resource'));
console.log(is_array([1, 2, 4, 0]));
false
true

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS Bin</title>
</head>
<body>
</body>
</html>

JavaScript Code:

var is_array = function(input) {
  if (toString.call(input) === "[object Array]")
    return true;
  return false;   
    };
console.log(is_array('w3resource'));
console.log(is_array([1, 2, 4, 0]));

Sample Output:

false
true

Flowchart:

Flowchart: JavaScript: Display the colors entered in an array by a specific format

ES6 Version:

var is_array = input => {
  if (toString.call(input) === "[object Array]")
    return true;
  return false;   
    };
console.log(is_array('w3resource'));
console.log(is_array([1, 2, 4, 0]));

Live Demo:

See the Pen JavaScript - Get the first element of an array- array-ex-1 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

if condition within the forEach loop

let count = 0;
const nums = [0, 1, 2, 3];

nums.forEach(num => {
	if (num) count += 1
})

console.log(count)

The if condition within the forEach loop checks whether the value of num is truthy or falsy. Since the first number in the nums array is 0, a falsy value, the if statement's code block won't be executed. count only gets incremented for the other 3 numbers in the nums array, 1, 2 and 3. Since count gets incremented by 1 3 times, the value of count is 3.

Ref: https://bit.ly/2Hcpkm6