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Node.js util.types.isAsyncFunction() Method

  • Last Updated : 10 Dec, 2021

The util.types.isAsyncFunction() method is an inbuilt application programming interface of the util module which is used to type check for asynchronous functions in the node.js.
Syntax: 

util.types.isAsyncFunction( value )

Parameters: This method accepts single parameter as mentioned above and described below: 

  • value: It is a required parameter that holds any datatype.

Return Value: It returns a boolean value, TRUE if the value is an async function from the perspective of the JavaScript engine, FALSE otherwise.
Below examples illustrate the use of util.types.isAsyncFunction() method in Node.js:
Example 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));

Output: 

true
false

Example 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");

Output: 

The passed value is an Async function.
The passed value is not an Async function

Note: The above program will compile and run by using the node filename.js command.
Reference: https://nodejs.org/api/util.html#util_util_types_isasyncfunction_value


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