Node.js util.types.isAsyncFunction() Method
Last Updated :
25 Apr, 2025
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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 a single parameter as mentioned above and described below:
- value: It is a required parameter that holds any data type.
Return Value: It returns a boolean value, TRUE if the value is an async function from the perspective of the JavaScript engine, FALSE otherwise.
The below examples illustrate the use of util.types.isAsyncFunction() method in Node.js:
Example 1:
// 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
let f2 = async function function2() { }
let 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:
// Node.js program to demonstrate the
// util.types.isAsyncFunction() Method
// Allocating util module
const util = require('util');
// Functions to be passed as parameter
const f2 = async function function2() { }
const 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
