Jquery – Using $.post within a javascript function, cannot assign value to a variable

globaljquerypostvariables

I'm trying to use $.post within a function, get the results, then return the function true or false based on the results of the $.post callback. However, the callback seems to occur, AFTER the return event of the parent function.

Here's the current code the ret variable is always undefined but if I alert() it within the $.post callback, it returns the correct result;

function elementExists(key, type, path, appid, pid){
    var ret;
    $.post('?do=elExists', {key: key, type: type, path: path, appid: appid, pid: pid},function(data){
        ret = data;                         
    });

    alert(ret);
    return ret;

}

Best Solution

As you've discovered the post is done asynchronously. If you want it to be synchronous, you'll need to use the ajax method and set the async parameter to false. It would be better, however, to acknowledge that the post is asynchronous and build your code so that the action performed by the callback is independent of the method that invokes the post. Obviously, you really want to do something other than the alert, but without knowing what it's hard to advise you how to refactor this.

EDIT: I understand that your code is checking to see if something exists, but it is checking that for a purpose. If we knew what the purpose was, then it might be possible to recommend how to accomplish that in the callback so that the method could be refactored.

Dynamically create `<input>`s in a form and submit it

/**
 * sends a request to the specified url from a form. this will change the window location.
 * @param {string} path the path to send the post request to
 * @param {object} params the parameters to add to the url
 * @param {string} [method=post] the method to use on the form
 */

function post(path, params, method='post') {

  // The rest of this code assumes you are not using a library.
  // It can be made less verbose if you use one.
  const form = document.createElement('form');
  form.method = method;
  form.action = path;

  for (const key in params) {
    if (params.hasOwnProperty(key)) {
      const hiddenField = document.createElement('input');
      hiddenField.type = 'hidden';
      hiddenField.name = key;
      hiddenField.value = params[key];

      form.appendChild(hiddenField);
    }
  }

  document.body.appendChild(form);
  form.submit();
}

Example:

post('/contact/', {name: 'Johnny Bravo'});

EDIT: Since this has gotten upvoted so much, I'm guessing people will be copy-pasting this a lot. So I added the hasOwnProperty check to fix any inadvertent bugs.

Python – the naming convention in Python for variable and function names

See Python PEP 8: Function and Variable Names:

Function names should be lowercase, with words separated by underscores as necessary to improve readability.

Variable names follow the same convention as function names.

mixedCase is allowed only in contexts where that's already the prevailing style (e.g. threading.py), to retain backwards compatibility.

Best Solution

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Python – the naming convention in Python for variable and function names

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