How to Check if a Variable is an Integer in JavaScript?

Checking if a Variable is an Integer in JavaScript

When working with JavaScript, it's common to need to check the type of a variable. If you need to verify whether a particular variable is an integer, follow these steps:

Using a Function

1. Define a function called isInt():

function isInt(value) {
  return !isNaN(value) && parseInt(Number(value)) == value && !isNaN(parseInt(value, 10));
}

2. Call the isInt() function with the variable you want to check:

isInt(22); // returns true
isInt("22.5"); // returns false

Using Bitwise Operations

1. Perform the following check:

(x | 0) === x

Where x is the variable you want to check.

For example:

42 | 0 === 42 // returns true
42.1 | 0 === 42 // returns false

Note:

• If you want to include strings that can be coerced into integers as integers, use the function method.
• If performance is critical, consider the bitwise operation with short-circuiting:

var x;
if (isNaN(value)) {
  return false;
}
x = parseFloat(value);
return (x | 0) === x;

• For a more concise version:

return isNaN(value) ? !1 : (x = parseFloat(value), (0 | x) === x);

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