Check number is float javascript

[Solved-6 Solutions] How do we check that a number is float or integer — javascript tutorial

If you want Simply solve this problem by using a simple regular expression.

 function isInt_number(v) < var num = /^-?4+$/; return er.test(value); >function isFloat_number(v) < var num = /^[-+]?6+\.4+$/; return num.test(v); >

Solution 2:

Check the modules of a number when its dividing by 1:

The above solution doesn’t give the clear idea about the argument is number or not then we use two methods to find if the number is integer or float.

 function isInt_number(num) < return Number(num) === num && num % 1 === 0; >function isFloat_number(num) 

Solution 3:

The above solution will also return true for an empty string. Try an alter function to avoid those confusion whether test a value is a number primitive value that has no fractional part and is within the size limits of what can be represented as an exact integer.

 function isFloat_number(num) < return num === +num && num!== (num|0); >function isInt_number(num) 

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Solution 4:

The better way to solve the problem is

 var isInt_number = function(num) < return parseInt(num) === num >; 

Solution 5:

We also use Number.isInteger() method which is currently implemented in latest Firefox. But still is a part of EcmaScript 6 proposal however MDN provides a polyfill for the other browsers to match the specified one in ECMA harmony:

 if (!Number.isInteger) < Number.isInteger = function isInt_number (num_value) < return typeof num_value === "number" && isFinite(num_value) && num_value >-9007199254740992 && num_value < 9007199254740992 && Math.floor(num_value) === num_value; >; > 

Solution 6:

There is a efficient functions that check if the value is a number or not. It define a value is not a number then the value can be safely converted to a number:

 function isNum(v) < if ((undefined === v) || (null === v)) < return false; >if (typeof v == 'num') < return true; >return !isNaN(v - 0); > 

This solution return false when a value is float that why we use another evaluated method:

 function isInteger(value) < if ((undefined === value) || (null === value)) < return false; >return value % 1 == 0; > 

• The parseInt (or parseNumber) are avoided when the value already is a number.
• Because the parsing functions always convert to string first and then attempt to parse that string, which would be a waste if the value already is a number.

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Check number is float javascript

Last updated: Dec 27, 2022
Reading time · 4 min

# Check if a value is a Float or an Integer in JavaScript

To check if a value is a float or an integer:

1. Use the Number.isInteger() method to check if a value is an integer.
2. Check if the value has a type of number and is not an integer or NaN to check if the value is a float.

Copied! 
// ✅ check if a value is a float function isFloat(value)  if ( typeof value === 'number' && !Number.isNaN(value) && !Number.isInteger(value) )  return true; > return false; > console.log(isFloat(1)); // 👉️ false console.log(isFloat(1.5)); // 👉️ true console.log(isFloat(-1.5)); // 👉️ true console.log(isFloat('1.5')); // 👉️ false 

To check if a number is a float, check if the value has a type of number and is not an integer or NaN .

We first check if the provided value has a type of number. If it doesn’t we return false straight away.

Copied! 
function isFloat(value)  if ( typeof value === 'number' && !Number.isNaN(value) && !Number.isInteger(value) )  return true; > return false; > 

We used the logical AND (&&) operator to check for multiple conditions. For our if block to run, all conditions have to be met.

The second condition checks if a value isn’t NaN (not a number). Unfortunately, NaN has a type of number in JavaScript.

Copied! 
console.log(typeof Number.NaN); // 👉️ number 

If the provided value is of type number , is not NaN and is not an integer, then the value is a floating-point number.

# Checking if a value is an integer

We used the Number.isInteger() method to check if a value is an integer.

Copied! 
console.log(Number.isInteger(1)); // 👉️ true console.log(Number.isInteger('1')); // 👉️ false console.log(Number.isInteger(1.5)); // 👉️ false 

There is a catch when using the Number.isInteger() method.

It returns true if the passed-in value:

Here’s an example of a float that can be represented as an integer.

Copied! 
console.log(Number.isInteger(10.0)); // 👉️ true 

It depends on your use case whether you consider 10.0 to be an integer or float.

Our implementation of the function considers numbers like 1.0 and 5.0 to be integers.

# A custom function that checks if the value is int or float

You can combine the conditions into a single function to check if a value is a float or an integer.

Copied! 
function isIntOrFloat(value)  if (typeof value === 'number' && !Number.isNaN(value))  if (Number.isInteger(value))  console.log('The value is an integer', value); > else  console.log('The value is a floating-point number', value); > > else  console.log('The value is not a number', value); > > isIntOrFloat(1); // 👉️ The value is an integer 1 isIntOrFloat(1.5); // 👉️ The value is a floating-point number 1.5 isIntOrFloat('1'); // 👉️ The value is not a number 1 isIntOrFloat(5.0); // 👉️ The value is an integer 5 isIntOrFloat('test'); // 👉️ The value is not a number test 

The function first checks if the value is a number and is not NaN because NaN has a type of number in JavaScript.

If we enter the if block, we know that the value is a number.

The next step is to check if the value is an integer using the Number.isInteger() function.

If the value is an integer , the if block runs.

If the value is a number and is not an integer, then the value is a floating-point number and the else block runs.

If the initial conditional check fails and the value does not have a type of number or is NaN , then the value is not a number.

# Checking if the value is a valid integer using RegExp.test()

You can also use the RegExp.test() method to check if a value is a valid integer.

Copied! 
function isInteger(value)  return /^-?7+$/.test(value); > console.log(isInteger(12)); // 👉️ true console.log(isInteger(-12)); // 👉️ true console.log(isInteger(1.0)); // 👉️ true console.log(isInteger('1')); // 👉️ true console.log(isInteger(1.5)); // 👉️ false 

The RegExp.test method matches the specified regular expression against the supplied value and returns true if the regular expression is matched in the string and false otherwise.

The forward slashes / / mark the beginning and end of the regular expression.

The caret ^ matches the beginning of the input and the dollar sign $ matches the end of the input.

We used a hyphen to also allow for negative integers.

The question mark ? matches the preceding item (the minus) 0 or 1 times. In other words, the minus — might be there, or it might not be there.

The character class 3 matches the digits in the range.

The plus + matches the preceding item (the range of digits) one or more times.

If you ever need help reading a regular expression, check out this regular expression cheatsheet by MDN.

It contains a table with the name and the meaning of each special character with examples.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

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How to check if number is integer or float in javascript?

To check number is an integer or float, JavaScript provides isInteger() method just pass your number as a parameter and it will return true if the number is an integer or else false.

Today, I’m going to show How do I check if the number is an integer or float in Javascript, here I will use the javascript string isInteger() method, to check if a number is an integer or float.

What is a isInteger() method?#

The Number.isInteger() method determines whether the passed value is an integer.

Let’s start the today’s tutorial How do you check if the number is integer or float in JavaScript?

In the following example, we will create our custom function to check number is int or float, where we will also add some more conditions like the given parameter should be a number and after that, we will check number is integer or float.

// function to check if a number is a float or integer value  function validateNumber(x)   // check if the passed value is a number  if(typeof x == 'number' && !isNaN(x))  // check if it is integer  if (Number.isInteger(x))   console.log(`$x> is integer.`);  >  else   console.log(`$x> is a float value.`);  >  > else   console.log(`$x> is not a number`);  > >  validateNumber('hello'); validateNumber(44); validateNumber(3.4); validateNumber(-3.4); validateNumber(NaN); 

In the above program, we have taken examples of every possible value like parameter if string, number, positive value, a negative value, or NaN values. let’s check the output.

javascript, check if number is integer or float example

I hope it’s help you, All the best 👍.

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JavaScript Program to Check if a Number is Float or Integer

To understand this example, you should have the knowledge of the following JavaScript programming topics:

Example 1: Using Number.isInteger()

// program to check if a number is a float or integer value function checkNumber(x) < // check if the passed value is a number if(typeof x == 'number' && !isNaN(x))< // check if it is integer if (Number.isInteger(x)) < console.log(`$is integer.`); > else < console.log(`$is a float value.`); > > else < console.log(`$is not a number`); > > checkNumber('hello'); checkNumber(44); checkNumber(3.4); checkNumber(-3.4); checkNumber(NaN);

hello is not a number 44 is integer. 3.4 is a float value. -3.4 is a float value. NaN is not a number

In the above program, the passed value is checked if it is an integer value or a float value.

• The typeof operator is used to check the data type of the passed value.
• The isNaN() method checks if the passed value is a number.
• The Number.isInteger() method is used to check if the number is an integer value.

Example 2: Using Regex

// program to check if a number is a float or integer value function checkNumber(x) < let regexPattern = /^-?4+$/; // check if the passed number is integer or float let result = regexPattern.test(x); if(result) < console.log(`$is an integer.`); > else < console.log(`$is a float value.`) > > checkNumber(44); checkNumber(-44); checkNumber(3.4); checkNumber(-3.4);

44 is an integer. -44 is an integer. 3.4 is a float value. -3.4 is a float value.

In the above example, the regex pattern is used to check if the passed argument is an integer value or float value.

The pattern /^-?7+$/ looks for the integer value.

The test() method of the RegExp object is used to test the pattern with the given value.

Note: The above program only works for numbers.

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