javascript - 数値と数値オブジェクトの違いは何ですか?

Question

通常の変数に格納されている数値の違いは何ですか:

var foo = 5; 

そして数値オブジェクト:

var bar = new Number(5);

数値オブジェクトは何に使用できますか?

Answer 1

オブジェクトには、次のNumberような便利なメソッドとプロパティが含まれています。

Number オブジェクト メソッド

Method                       Description
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
toExponential(x)    Converts a number into an exponential notation
toFixed(x)          Formats a number with x numbers of digits after the decimal point
toPrecision(x)      Formats a number to x length
toString()          Converts a Number object to a string
valueOf()           Returns the primitive value of a Number object

Number オブジェクトのプロパティ

Property                        Description
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
constructor         Returns the function that created the Number object's prototype
MAX_VALUE       Returns the largest number possible in JavaScript
MIN_VALUE           Returns the smallest number possible in JavaScript
NEGATIVE_INFINITY   Represents negative infinity (returned on overflow)
NaN             Represents a "Not-a-Number" value
POSITIVE_INFINITY   Represents infinity (returned on overflow)
prototype           Allows you to add properties and methods to an object