user defined function with callback in nodejs

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抹茶落季
抹茶落季 2021-02-14 03:13

can anyone give me an example in which we are creating a particular function, which is also having a callback function ?

function login(username, password, funct         


        
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  • 2021-02-14 03:48

    Here's an example of the login function:

    function login(username, password, callback) {
        var info = {user: username, pwd: password};
        request.post({url: "https://www.adomain.com/login", formData: info}, function(err, response) {
            callback(err, response);
        });
    }
    

    And calling the login function

    login("bob", "wonderland", function(err, result)  {
        if (err) {
            // login did not succeed
        } else {
            // login successful
        }
    });
    
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  • 2021-02-14 03:57

    bad question but w/e
    you have mixed up invoking and defining an asynchronous function:

    // define async function:
    function login(username, password, callback){
      console.log('I will be logged second');
      // Another async call nested inside. A common pattern:
      setTimeout(function(){
        console.log('I will be logged third');
        callback(null, {});
      }, 1000);
    };
    
    //  invoke async function:
    console.log('I will be logged first');
    login(username, password, function(err,result){
      console.log('I will be logged fourth');
      console.log('The user is', result)
    });
    
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