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Javascript Number Methods

JavaScript provides various built-in methods for working with numbers.

Here are some of the most commonly used ones:

  • toString(): Converts a number to a string.
let num = 42;
console.log(num.toString()); // "42"
  • toFixed(): Formats a number with a specified number of decimal places and returns a string representation of the result.
let num = 3.14159;
console.log(num.toFixed(2)); // "3.14"
  • parseInt(): Converts a string to an integer.
let str = "42";
console.log(parseInt(str)); // 42
  • parseFloat(): Converts a string to a floating-point number.
let str = "3.14159";
console.log(parseFloat(str)); // 3.14159
  • isNaN(): Determines whether a value is NaN (Not-a-Number).
let num = "hello";
console.log(isNaN(num)); // true
  • Math.round(): Rounds a number to the nearest integer.
let num = 3.7;
console.log(Math.round(num)); // 4
  • Math.max(): Returns the largest number in a list of arguments.
console.log(Math.max(1, 2, 3)); // 3
  • Math.min(): Returns the smallest number in a list of arguments.
console.log(Math.min(1, 2, 3)); // 1
  • Math.random(): Returns a random number between 0 and 1.
console.log(Math.random()); // 0.123456789
  • toExponential(): This method returns a string representation of a number in exponential notation.
let x = 123456;
console.log(x.toExponential(2)); // "1.23e+5"
  • toPrecision(): This method returns a string representation of a number with a specified number of total digits.
let x = 1234.56;
console.log(x.toPrecision(3)); // "1.23e+3"
  • isFinite(): This method determines whether a value is a finite number.
console.log(isFinite(123)); // true
console.log(isFinite(Infinity)); // false
  • Math.ceil(): This method rounds up a number to the nearest integer.
console.log(Math.ceil(1.5)); // 2
  • Number(): This method converts a value to a number.
console.log(Number("123")); // 123
  • Math.floor(): This method rounds down a number to the nearest integer.
console.log(Math.floor(1.5)); // 1

These are just a few of the many number methods available in JavaScript. By using these methods, you can perform a wide range of mathematical operations on numbers in your code.

Converting Variables to Numbers​

JavaScript provides several methods for converting variables to numbers. Here are some of the most commonly used ones:

  • parseInt(): This method parses a string and returns an integer. It takes two optional arguments: the base (radix) of the number being parsed and the index of the first character to be parsed.
let num = parseInt("123");
console.log(num); // 123
  • parseFloat(): This method parses a string and returns a floating-point number.
let num = parseFloat("3.14");
console.log(num); // 3.14
  • Number(): This method converts a value to a number.
let num = Number("123");
console.log(num); // 123
  • unary plus operator (+): This operator converts a value to a number. It can be used as a shorthand for the Number() method.
let num = +"123";
console.log(num); // 123
info

Converting variables to numbers can result in NaN for certain values, such as unparsable strings or undefined variables.

console.log(parseInt("hello")); // NaN
console.log(Number(undefined)); // NaN

Number Object Methods​

Here are some commonly used methods of the Number object in JavaScript:

  • Number.isNaN(): This method determines whether a value is NaN (Not a Number).
console.log(Number.isNaN("hello")); // false
console.log(Number.isNaN(NaN)); // true
  • Number.isFinite(): This method determines whether a value is a finite number.
console.log(Number.isFinite(123)); // true
console.log(Number.isFinite(Infinity)); // false
  • Number.isInteger(): This method determines whether a value is an integer.
console.log(Number.isInteger(5)); // true
console.log(Number.isInteger(5.1)); // false
  • Number.parseInt(): This method parses a string and returns an integer. It takes two optional arguments: the string to be parsed and the base (radix) of the number being parsed.
let num = Number.parseInt("123");
console.log(num); // 123
  • Number.parseFloat(): This method parses a string and returns a floating-point number.
let num = Number.parseFloat("3.14");
console.log(num); // 3.14
  • Number.toFixed(): This method returns a string representation of a number with a fixed number of digits after the decimal point.
let num = 3.14159;
console.log(num.toFixed(2)); // "3.14"
  • Number.toPrecision(): This method returns a string representation of a number with a specified number of total digits.
let num = 1234.5678;
console.log(num.toPrecision(4)); // "1235"
  • Number.MAX_VALUE: This property returns the largest representable number in JavaScript.
console.log(Number.MAX_VALUE); // 1.7976931348623157e+308
  • Number.MIN_VALUE: This property returns the smallest representable number in JavaScript.
console.log(Number.MIN_VALUE); // 5e-324

By using these methods, you can perform a variety of operations on numbers in JavaScript, such as checking for NaN or finite values, parsing strings as numbers, and formatting numbers for display.