JavaScript: Check whether a value is an integer or not

JavaScript Math: Exercise-15 with Solution

Check If Value is Integer

Write a JavaScript function to check whether a value is an integer or not.

Test Data:
console.log(is_Int(23));
console.log(is_Int(4e2));
console.log(is_Int(NaN));
console.log(is_Int(23.75));
console.log(is_Int(-23));
Output :
true
true
false
false
true

Visual Presentation:

Sample Solution:

JavaScript Code:

// Define a function named is_Int that checks if a number is an integer.
function is_Int(num) {
    // Check if the input is not a number, if so, return false.
    if (typeof num !== 'number')
        return false; 
    // Check if the number is not NaN, if its integer representation equals itself, and if parsing it as an integer with base 10 does not result in NaN.
    return !isNaN(num) && 
           parseInt(Number(num)) == num && 
           !isNaN(parseInt(num, 10));
}

// Output the result of checking if 23 is an integer to the console.
console.log(is_Int(23));
// Output the result of checking if 4e2 is an integer to the console.
console.log(is_Int(4e2));
// Output the result of checking if NaN is an integer to the console.
console.log(is_Int(NaN));
// Output the result of checking if 23.75 is an integer to the console.
console.log(is_Int(23.75));
// Output the result of checking if -23 is an integer to the console.
console.log(is_Int(-23));

Output:

true
true
false
false
true

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-15 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that checks if a value is an integer using Number.isInteger and fallback logic for older browsers.
• Write a JavaScript function that determines integer status by comparing Math.floor and Math.ceil of the value.
• Write a JavaScript function that tests if a value is an integer after converting numeric strings, handling edge cases.
• Write a JavaScript function that uses bitwise operations to check if a value is an integer and returns a boolean.

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