CODEWITHSUNDEEP
javascript
Faraday Plissken
Faraday Plissken

Reputation: 67

Why does my JavaScript console always says undefined

This piece of code should send a message in WhatsApp Web, on entering it to the JavaScript console, but it always says undefined.

How can I prevent this?

function whatsAppText(t) {
  window.InputEvent = window.Event || window.InputEvent;
  var d = new Date();
  var event = new InputEvent('input', {bubbles: true});
  var textbox = document.querySelector('#main > footer > div.block-compose > div.input-container > div > div.input');
  textbox.textContent = t;
  textbox.dispatchEvent(event);
  document.querySelector('.icon.btn-icon.icon-send.send-container').click()
}

Upvotes: 2

Views: 616

Answers (2)

Scott Marcus
Scott Marcus

Reputation: 65806

The console will report the returned value of an expression. If a function does something meaningful, but does not return anything, then executing the function returns nothing, hence undefined.

Here is an example:

function foo(){
  document.body.innerHTML = "<p>I did some work, but I didn't return a value.</p>";
}

console.log(foo());  // undefined

As opposed to:

function foo(){
  return "I did some work, and I did return a value.";
}

console.log(foo());  // "I did some work, and I did return a value."

But, if all you are doing is entering the function into your console and not even calling it, that won't return anything and the console will report undefined. Based on the code you've shown, even if you then invoke your function with, say: whatsAppText("test"), your function will execute and send the message, but you don't have your function set up to return anything, so you'll still see undefined.

Upvotes: 2

Fabio
Fabio

Reputation: 791

That's because you are only defining a function and not executing it. You have to call the function somewhere after it's been declared:

whatsAppText('This should work!');

Upvotes: 0

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