Passing variables to $.ajax().done()

jquery ajax loops promise scoping

15,983

Solution 1

You can use a closure (via a self executing function) to capture the value of i for each invocation of the loop like this:

for (var i in obj) {
    (function(index) {
        // you can use the variable "index" here instead of i
        $.ajax(/script/).done(function(data){ console.log(data); });
    })(i);
}

Solution 2

You can just create a custom field in the object that you send to $.ajax(), and it will be a field in this when the promise callback is made.

For example:

$.ajax( { url: "https://localhost/whatever.php", method: "POST", data: JSON.stringify( object ), custom: i // creating a custom field named "custom" } ).done( function(data, textStatus, jqXHR) { var index = this.custom; } );

15,983

Author by

Phil Tune

(2015) I do front-end development for a small company in East TN. I'm a StackOverflow enthusiast and tend to click here before even MDN for most Google searches. I am fanatic about general performance and accessibility. My SO questions tend to be about experimental concepts. I like building my own tools (re-re-reinventing the wheel) for its own sake. I'm obsessed with producing elegant, readable code. I'm very OCD (though my mother has never had me tested) and proud of it; I will rewrite projects several times and feel like it was time well-spent as long as it produces even a marginally better product. I love reading about new technologies and W3C rec's, but as my company's stuck on supporting IE8 (and graceful degradation can be a pain) I've yet to experiment with a lot of the new browser implementations, let alone the experimental stuff. I love jQuery but find myself lately trying to use it less and less in favor of vanilla js. As for other libraries I tend to be very averse and prefer custom options, even if it's more work - learning is never a wasted effort. My wife and I - both transplants from southeast Missouri - live right next to the Smoky Mountains and regularly serve in ministries at our local church. We don't have cable or smartphone data plans but watch a lot of Netflix. We like all natural foods (though I'd never turn down a bag of Doritos) and love to visit farms and do other "free" activities.

Updated on June 12, 2022

Comments

Phil Tune almost 2 years
I'm lost. How might I pass a loop variable to an AJAX .done() call?
```
for (var i in obj) {
   $.ajax(/script/).done(function(data){ console.log(data); });
}
```
Obviously, if I were to do console.log(i+' '+data) i would return the very last key in the object obj on every single iteration. Documentation fails me.
Phil Tune about 12 years

Closures are one concept I've always had a tough time understanding fully. Thanks @jfriend00, I'ma try that!
Phil Tune about 12 years

Yep, that worked. I could even do obj[index]. Thanks again!
Phil Tune over 7 years

After 5 years, I have long since forgotten what even prompted this question. ;)
Darwin Airola over 7 years

I needed to know how to do this for a recent project. So, when I figured it out, I tried to also relay the information to others who said that they wanted it...
Deep Saurabh almost 7 years

This is better from jquery ajax asynchronous execution point of view, it clearly provide intended item/object reference when callback is executed latter in time.