Node.js util.types.isPromise() Method
Last Updated :
04 Apr, 2023
The util.types.isPromise() method is an inbuilt application programming interface of the util module which is primarily designed to support the needs of Node.js own internal APIs. The util.types.isPromise() method is used to determine whether the value is a built-in Promise.
Syntax:
util.types.isPromise( value )
Parameter: This method accepts a single parameters value that holds any valid JavaScript data types like Boolean, Null, Number, Object, etc.
Return value: It returns a Boolean value i.e. returns true if the value is a built-in Promise otherwise it returns false.
The below examples illustrate the use of util.types.isPromise() method in Node.js:
Example 1:
javascript
const util = require( 'util' );
console.log(util.types.isPromise( true ));
console.log(util.types.isPromise( new Set()));
console.log(util.types.isPromise(
new Promise( function (resolve, reject) { })));
|
Output:
false
false
true
Example 2:
javascript
const util = require( 'util' );
console.log(util.types.isPromise( true ));
console.log(util.types.isPromise( new Set()));
const promise = new Promise( function (resolve, reject) {
const x = "geeksforgeeks" ;
const y = "geeksforgeeks"
if (x === y) {
resolve();
} else {
reject()
}
});
console.log(util.types.isPromise(promise.
then( function () {
console.log( 'Success, You are a GEEK' );
}).
catch ( function () {
console.log( 'Some error has occurred' );
})
));
|
Output:
false
false
true
Success, You are a GEEK
Note: The above program will compile and run by using the node index.js command.
Reference: https://nodejs.org/dist/latest-v13.x/docs/api/util.html#util_util_types_ispromise_value
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