Node.js util.types.isBoxedPrimitive() 方法

util.types.isBoxedPrimitive() 方法是util模块的内置应用程序编程接口，主要用于支持 Node.js 自身内部 API 的需求。

util.types.isBoxedPrimitive() 方法用于检查给定值是否为盒装图元。

句法：

util.types.isBoxedPrimitive( value )

参数：此函数接受一个如上所述和如下所述的参数：

• value：它是为盒装原语检查的值。

返回值：它返回一个布尔值，即如果传递的值是一个装箱的原语，则返回 true，否则返回false 。

下面的示例说明了 Node.js 中的util.types.isBoxedPrimitive() 方法：

示例 1：

// Node.js program to demonstrate the    
// util.types.isBoxedPrimitive() method
  
// Import the util module
const util = require('util');
  
// Checking an unboxed string
let unboxedString = "GeeksforGeeks";
console.log("Value:", unboxedString);
isBoxed = util.types.isBoxedPrimitive(unboxedString);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking a boxed string
let boxedString = new String("GeeksforGeeks");
console.log("Value:", boxedString);
isBoxed = util.types.isBoxedPrimitive(boxedString);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking an unboxed integer
let unboxedInteger = 99;
console.log("Value:", unboxedInteger);
isBoxed = util.types.isBoxedPrimitive(unboxedInteger);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking a boxed integer
let boxedInt = new Number(99);
console.log("Value:", boxedInt);
isBoxed = util.types.isBoxedPrimitive(boxedInt);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking an unboxed boolean
let unboxedBool = false;
console.log("Value:", unboxedBool);
isBoxed = util.types.isBoxedPrimitive(unboxedBool);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking a boxed boolean
let boxedBool = new Boolean(false);
console.log("Value:", boxedBool);
isBoxed = util.types.isBoxedPrimitive(boxedBool);
console.log("Value is a boxed primitive:", isBoxed);

输出：

Value: GeeksforGeeks
Value is a boxed primitive: false
Value: [String: 'GeeksforGeeks']
Value is a boxed primitive: true
Value: 99
Value is a boxed primitive: false
Value: [Number: 99]
Value is a boxed primitive: true
Value: false
Value is a boxed primitive: false
Value: [Boolean: false]
Value is a boxed primitive: true

示例 2：

// Node.js program to demonstrate the    
// util.types.isBoxedPrimitive() method
  
// Import the util module
const util = require('util');
  
// Checking for the symbol primitive
let symbol = Symbol('geeks');
console.log("Value:", symbol);
isBoxed = util.types.isBoxedPrimitive(symbol);
console.log("Value is a boxed primitive:", isBoxed);
  
// Checking again after creating a symbol wrapper
let symbolObj = new Object(Symbol('geeks'));
console.log("Value:", symbolObj);
isBoxed = util.types.isBoxedPrimitive(symbolObj);
console.log("Value is a boxed primitive:", isBoxed);

Value: Symbol(geeks)
Value is a boxed primitive: false
Value: [Symbol: Symbol(geeks)]
Value is a boxed primitive: true

参考： https://nodejs.org/api/util.html#util_util_types_isboxedprimitive_value