How to return value from call back?

Question

When I use alert() or console.log() it works properly.

function greeting(name) {
  alert('Hello ' + name);
  console.log(`Hello ${name}`)
}

function processUserInput(callback) {
  var name = prompt('Please enter your name.');
  callback(name);
}

processUserInput(greeting);

But when I use return it returns undefined

function greeting(name) {
    let returnthis = `hello ${name}`
    return returnthis
  }


  
  function processUserInput(callback) {
    var name = prompt('Please enter your name.');
    callback(name);
  }
  
  console.log(processUserInput(greeting));

Why is this happening?

How to return value?

I read this answer but can't understand.

simply add return `return callback(name);` – lankovova Apr 21 '19 at 12:24 — lankovova, Apr 21 '19 at 12:24

score 2 · Accepted Answer · answered Apr 21 '19 at 12:25

2

You need to return callback also

function greeting(name) {
  return `hello ${name}`
}



function processUserInput(callback) {
  var name = prompt('Please enter your name.');
  return callback(name);
}

console.log(processUserInput(greeting));

answered Apr 21 '19 at 12:25

prasanth

22,145
4
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score 2 · Answer 2 · answered Apr 21 '19 at 12:25

2

Because processUserInput returns nothing. Do:

  return callback(name);

answered Apr 21 '19 at 12:25

Jonas Wilms

132,000
20
149
151

How to return value from call back?

2 Answers2