JavaScript: Check whether an 'input' is a string or not

JavaScript String: Exercise-1 with Solution

Check String Input

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

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

Visual Presentation:

Sample Solution:

JavaScript Code:

// Define a function named is_string that takes an input parameter
is_string = function(input) {
  // Check if the type of input is a string by examining its internal [[Class]] property
  if (Object.prototype.toString.call(input) === '[object String]')
    // Return true if the input is a string
    return true;
  else
    // Return false if the input is not a string
    return false;   
    };
// Output the result of calling the is_string function with a string argument
console.log(is_string('w3resource'));
// Output the result of calling the is_string function with an array argument
console.log(is_string([1, 2, 4, 0]));

Output:

true
false

Explanation:

In the exercise above,

• The "is_string()" function is defined, taking one parameter as input.
• Inside the function, it checks the type of 'input' by using Object.prototype.toString.call('input').
• If the result of this check matches the string '[object String]', it returns 'true', indicating that the input is a string.
• Otherwise, it returns 'false', indicating that the input is not a string.
• The function definition ends.
• Two examples are provided to demonstrate the "is_string()" function with different types of input: a string ('w3resource') and an array ([1, 2, 4, 0]).
• The results of calling "is_string()" with these inputs are printed to the console using console.log.

Flowchart:

Live Demo:

See the Pen JavaScript Print an integer with commas as thousands separators - string-ex-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that checks if a variable is of type string using typeof and Object.prototype.toString.
• Write a JavaScript function that determines if an input is a string by verifying it has a substring method.
• Write a JavaScript function that accepts various inputs and returns true only for string primitives (not String objects).
• Write a JavaScript function that tests an input and returns a custom error if it is not a string.

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