JavaScript: Get the first element of an array

JavaScript Array: Exercise-1 with Solution

Check Array Input

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:

JavaScript Code:

// Function to check if the input is an array
var is_array = function(input) {
  // Using toString method to get the class of the input and checking if it is "[object Array]"
  if (toString.call(input) === "[object Array]")
    // Return true if the input is an array
    return true;
  // Return false if the input is not an array
  return false;   
};

// Testing the function with a string
console.log(is_array('w3resource'));

// Testing the function with an array
console.log(is_array([1, 2, 4, 0]));

Output:

false
true

Flowchart:

ES6 Version:

// Function to check if the input is an array
const is_array = input => {
  // Using toString method to get the class of the input and checking if it is "[object Array]"
  if (toString.call(input) === "[object Array]") {
    // Return true if the input is an array
    return true;
  }
  // Return false if the input is not an array
  return false;
};

// Testing the function with a string
console.log(is_array('w3resource'));

// Testing the function with an array
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.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that checks if a given variable is an array using Array.isArray and also confirms its length property exists.
• Write a JavaScript function that determines if an input is an array by examining its constructor and Object.prototype.toString output.
• Write a JavaScript function that distinguishes between arrays and array-like objects by testing for the push method.
• Write a JavaScript function that checks whether an input is a true array and returns a custom error message if not.

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