How to check value is decimal or not in javascript?

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This tutorial will help you to check value is decimal or not in javascript, here we will you below three ways to check decimal numbers.

1. Javascript Number.isInteger() Method
2. Javascript Math.floor() Method
3. Javascript indexOf() Method

Let’s start today’s tutorial How to check value is decimal or not in javascript?

Javascript Number.isInteger() Method

Javascript provide Number.isInteger() to identify given data is whole number or decimal number.

!Number.isInteger(12.00);  // false
!Number.isInteger(12);    // false
!Number.isInteger(-12);  // false
!Number.isInteger(-12.003);  // true
!Number.isInteger(25.00000000000001);  // true
!Number.isInteger(25.00000000000000001);  // false

Number.isInteger() is part of the ES6 standard, and you are using an older version, you have should move to the second solution.

Note: Number.isInteger() to find the decimal place, you have “.” After and before 13 digits, the value must be greater than 0.

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Javascript Math.floor() Method

For check decimal number, we will use Javascript Math.floor() Method, it will same work like Number.isInteger() method.

function isDecimal(n) {
  var result = n - Math.floor(n) !== 0;

  if (result) return true;
  else return false;
}

console.log(isDecimal(12.00));  // false
console.log(isDecimal(12));  // false
console.log(isDecimal(-12));  // false
console.log(isDecimal(-12.002));  // true
console.log(isDecimal(25.000000000001));  // true
console.log(isDecimal(25.000000000000001));  // false

Note: isDecimal(n) to find the decimal place, you have “.” After and before 13 digits, the value must be greater than 0.

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Javascript indexOf() Method

If you want to get isDecimal to provide true when you pass 0.00, and 12.00 then you will help indexOf() Method, it only checks “.” in provided value, and if it is available it will return true.

!("12.00".indexOf(".") == -1);  // true
!("12".indexOf(".") == -1);  // false
!("-12".indexOf(".") == -1);  // false
!("-12.003".indexOf(".") == -1);  // true
!("25.00000000000001".indexOf(".") == -1);  // true
!("25.00000000000000001".indexOf(".") == -1);  // true

Note: to use indexOf() method you have to first convert value number to string.

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