Node.js util.types.isAsyncFunction() 方法
util.types.isAsyncFunction() 方法是 util 模块的内置应用程序编程接口,用于对 node.js 中的异步函数进行类型检查。
句法:
util.types.isAsyncFunction( value )
参数:此方法接受上面提到的单个参数,如下所述:
- value:它是保存任何数据类型的必需参数。
返回值:它返回一个布尔值,如果从 JavaScript 引擎的角度来看该值是一个异步函数,则返回 TRUE,否则返回 FALSE。
以下示例说明了 Node.js 中 util.types.isAsyncFunction() 方法的使用:
示例 1:
javascript
// Node.js program to demonstrate the
// util.types.isAsyncFunction() Method
// Allocating util module
const util = require('util');
// Functions to be passed as parameter of
// util.types.isAsyncFunction() method
var f2 = async function function2(){}
var f1 = function function1(){}
// Printing the returned value from
// util.types.isAsyncFunction() method
console.log(util.types.isAsyncFunction(f2));
console.log(util.types.isAsyncFunction(f1));
javascript
// Node.js program to demonstrate the
// util.types.isAsyncFunction() Method
// Allocating util module
const util = require('util');
// Functions to be passed as parameter
var f2 = async function function2() { }
var f1 = function function1() { }
// Calling util.types.isAsyncFunction() method
if (util.types.isAsyncFunction(f2))
console.log("The passed value is an Async function.");
else
console.log("The passed value is not an Async function");
if (util.types.isAsyncFunction(f1))
console.log("The passed value is an Async function.");
else
console.log("The passed value is not an Async function");
输出:
true
false
示例 2:
javascript
// Node.js program to demonstrate the
// util.types.isAsyncFunction() Method
// Allocating util module
const util = require('util');
// Functions to be passed as parameter
var f2 = async function function2() { }
var f1 = function function1() { }
// Calling util.types.isAsyncFunction() method
if (util.types.isAsyncFunction(f2))
console.log("The passed value is an Async function.");
else
console.log("The passed value is not an Async function");
if (util.types.isAsyncFunction(f1))
console.log("The passed value is an Async function.");
else
console.log("The passed value is not an Async function");
输出:
The passed value is an Async function.
The passed value is not an Async function
注意:上面的程序将使用 node filename.js 命令编译和运行。
参考: https://nodejs.org/api/util.html#util_util_types_isasyncfunction_value