How do I get the correct answer?

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Hi, I am new to JavaScript promise and async. I am having problem to get the correct value from the "TrueOrFalsefn()" show below,

JavaScript

// Objective: to return True/False from this function 
// 
function TrueOrFalsefn(){    
    var output = null;      
    //1. Create a new function that returns a promise
    if (secondFunction()== true)
	{
		alert("Yes"); 
		return true;  // <<--- 
	}
	else if (secondFunction()== false)
	{
		alert("No");
		return false;    
	}
     
	//2. Create an async function
    async function secondFunction() { 
        let result2 = await firstFunction()
		 if (result2==101 )
		 {
			 output = true;  
		 }
		 else{
			output = false;
		 }
         return output;
    }; 

	function firstFunction() {
      return new Promise((resolve, reject) => {
          let y = 100
          setTimeout(() => {           
             resolve(y+1)
          }, 2000)
      })
    }
}

What I have tried:

When debug in browser, result is always "null" but I am expecting "True" in return.

Can anyone advise how can I get it right?
Thanks in advance
Wilson

Posted 1-Oct-20 0:47am

CoderWil

Updated 1-Oct-20 1:04am

CPallini

v2

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Richard Deeming · Accepted Answer · 2020-10-01T01:05:00

The result of an async function will be a Promise. You either need to await it, or use the continuation to read the result.

You should also avoid calling the function twice. Call it once and store the result in a variable.

JavaScript

async function TrueOrFalsFn(){
    function firstFunction(){
        return new Promise((resolve, reject) => {
            let y = 100
            setTimeout(() => resolve(y + 1), 2000)
        });
    }
    
    async function secondFunction(){
        let result2 = await firstFunction();
        return result2 === 101;
    }
    
    let output = await secondFunction();
    if (output) {
        alert("Yes");
    }
    else {
        alert("No");
    }
    
    return output;
}

NB: The calling code will also need to await the result of this function, or use the continuation to read the result.