TypeScript Number Object

In TypeScript, number is a primitive data type used to represent numbers, including integers and floating-point numbers. In addition to this primitive type, there is a corresponding built-in object Number. The Number object is a wrapper object for the primitive number type, providing some properties and methods for working with numbers.

Typically, using the number type directly is sufficient. When you call a method on a number type variable (like toFixed()), JavaScript/TypeScript automatically wraps it in a temporary Number object behind the scenes to perform the operation.

Properties of the Number Object

The Number object provides some useful built-in properties that are static and can be accessed directly through Number.

• Number.MAX_VALUE: Represents the largest positive number that can be represented in JavaScript.

  console.log(Number.MAX_VALUE); // Approximately 1.797e+308

• Number.MIN_VALUE: Represents the smallest positive number that can be represented in JavaScript (the positive number closest to 0).

  console.log(Number.MIN_VALUE); // Approximately 5e-324

• Number.NaN: Represents the special "Not-a-Number" value. When an arithmetic operation returns an undefined or unrepresentable value, you get NaN.

  console.log(0 / 0); // NaN
  console.log(parseInt("hello")); // NaN

• Number.POSITIVE_INFINITY: Represents positive infinity.

  console.log(Number.POSITIVE_INFINITY); // Infinity
  console.log(1 / 0); // Infinity

• Number.NEGATIVE_INFINITY: Represents negative infinity.

  console.log(Number.NEGATIVE_INFINITY); // -Infinity
  console.log(-1 / 0); // -Infinity

Methods of the Number Object

These methods need to be called through an instance of the number type.

• toFixed(digits): Formats a number to a string with a specified number of decimal places. It performs rounding.

  let num = 123.45678;
  console.log(num.toFixed(2)); // "123.46"
  console.log(num.toFixed(0)); // "123"

• toPrecision(precision): Formats a number to a string with a specified total length (significant digits). It also performs rounding.

  let num = 123.45678;
  console.log(num.toPrecision(4)); // "123.5"
  console.log(num.toPrecision(7)); // "123.4568"
  console.log(num.toPrecision(2)); // "1.2e+2"

• toString(radix): Converts a number to a string representation in the specified base (radix). radix is an integer between 2 and 36. If omitted, defaults to 10.

  let num = 255;
  console.log(num.toString());    // "255" (decimal)
  console.log(num.toString(16));  // "ff" (hexadecimal)
  console.log(num.toString(8));   // "377" (octal)
  console.log(num.toString(2));   // "11111111" (binary)

• toExponential(fractionDigits): Returns a string representing the number in exponential notation. fractionDigits is optional and specifies the number of digits in the fractional part.

  let num = 12345;
  console.log(num.toExponential()); // "1.2345e+4"
  console.log(num.toExponential(2)); // "1.23e+4"

• toLocaleString(): Returns a localized string representation of the number. This is useful when displaying currency, dates, etc., as it formats numbers according to the user's locale settings.

  let largeNum = 1234567.89;
  // In US English locale
  console.log(largeNum.toLocaleString('en-US')); // "1,234,567.89"
  // In German locale
  console.log(largeNum.toLocaleString('de-DE')); // "1.234.567,89"

These methods provide powerful flexibility for handling and displaying numbers.