How to access additional arguments passed to bind javascript?

Question

I am trying to bind values to a function in a loop. How can I access the binded values in the function?

// ansswer number is is different each time
 btn.find("a").data(this.key, option.slide).bind("click", this._continueOnClick.bind(answerNumber));

Now from the function _continueOnClick, how can I actually access the value of answerNumber?

The function:

_continueOnClick: function (e) {
    console.log(answerNumber); //fails
}

[What is the use of the JavaScript 'bind' method?](https://stackoverflow.com/questions/2236747/what-is-the-use-of-the-javascript-bind-method) explains in details how `bind` can be used. The first argument passed to `bind` will be _found in_ `this`. — t.niese, Aug 26 '22 at 14:28
Not sure I can easily. Its extremely complex code written in ASP.NET and everything is dynamically created using classes — mcool, Aug 26 '22 at 14:31
That didn't work either. Prints the class as an object and the value I need isn't there — mcool, Aug 26 '22 at 14:36
`console.log(this)` has to work. If not then the code you show and the one you actually have do not match. — t.niese, Aug 26 '22 at 14:42
Please post a [mcve] of your attempt, noting input and expected output using the [\[<>\]](https://meta.stackoverflow.com/questions/358992/ive-been-told-to-create-a-runnable-example-with-stack-snippets-how-do-i-do) snippet editor. — mplungjan, Aug 26 '22 at 14:52

Keith · Accepted Answer · 2022-08-26T14:53:36.607

Bind's first parameter is what you want to pass as this, but it will expect an object here, if you send a primitive it will convert into the Object version, eg. number to Number(), so you could just use this.valueOf().

But another option, you can pass more params, you can just pass null or some other object as the first parameter. These extra params will then be available in the callback's parameters and can also be primitives, not just objects..

Here is an example..

for (let answerNum = 0; answerNum < 10; answerNum++) {
  const btn = document.createElement('button');
  btn.innerText = answerNum;
  document.body.appendChild(btn);
  btn.addEventListener('click', click.bind(null, answerNum));
}

function click(answerNum) {
  console.log(answerNum);
}

How to access additional arguments passed to bind javascript?

1 Answers1