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Async/Await + Ajax .done: Returning undefined – Jquery ajax

Sorry if this is extremely simple, I can’t get my head around it. I’ve seen similar questions but nothing which gets to the heart of my problem, I think. I have a simple async function:

async function isOpen() {

    var open;

    var data = $.ajax({
      //Working code here
    });

    data.done(function(dat) {
        var obj = JSON.parse(dat);
        var msg = "";

        for (var i = 0; i < obj.length; i++) {

            let closingDate = Date.parse(obj[i].close);
            let openingDate = Date.parse(obj[i].open);

            if (closingDate > Date.now() && openingDate < Date.now()) {
                open = true;
            } else {
                open = false;
            }
        }
    });

    return open;
}

I know that this code is all working – using console.log I have seen that open is always successfully assigned to true or false. So I call this async function from another async function:

async function testFunction(){

    const open1 = await isOpen();
    //More code here...

}

But open1 (in testFunction) is always undefined – even though I use await.

Any ideas what this could be?

Tags:

2

Answers


  1. 0 
    async function isOpen() {

    var open;

    var data = await $.ajax({
      //Working code here
    });

    var obj = JSON.parse(data);
    var msg = "";

    for (var i = 0; i < obj.length; i++) {

        let closingDate = Date.parse(obj[i].close);
        let openingDate = Date.parse(obj[i].open);

        if (closingDate > Date.now() && openingDate < Date.now()) {
            open = true;
        } else {
            open = false;
        }
    }
    return open;
}

    of course, the value of open will be determined by the last obj[i]

    So you want

    async function isOpen() {
    const data = await $.ajax({
      //Working code here
    });
    const obj = JSON.parse(data);
    let msg = "";

    for (var i = 0; i < obj.length; i++) {

        const closingDate = Date.parse(obj[i].close);
        const openingDate = Date.parse(obj[i].open);

        if (closingDate > Date.now() && openingDate < Date.now()) {
            return true;
        }
    }
    return false;
}

    Or even

    async function isOpen() {
    const data = await $.ajax({
      //Working code here
    });

    const obj = JSON.parse(data);
    let msg = "";
    return obj.some(({open, close}) => {
        const closingDate = Date.parse(close);
        const openingDate = Date.parse(open);
        const now = Date.now();
        return closingDate > now && openingDate < now();
    });
}
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  2. 0

    This is happening because you are using a callback for ajax request and not waiting for ajax request to complete, which is going to set open in isOpen. You can return a Promise to resolve this,

    function isOpen() {
  return new Promise((resolve, reject) => {
    var open;

    var data = $.ajax({
      //Working code here
    });

    data.done(function(dat) {
        var obj = JSON.parse(dat);
        var msg = "";

        for (var i = 0; i < obj.length; i++) {

            let closingDate = Date.parse(obj[i].close);
            let openingDate = Date.parse(obj[i].open);

            if (closingDate > Date.now() && openingDate < Date.now()) {
                open = true;
            } else {
                open = false;
            }
        }
       resolve(open);
    });

  }
}

    Note: For the above code, you need to handle the logic for errors in the callback, using reject otherwise it will hang forever.

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