Form OnSubmit to wait jQuery Ajax Return?

问题

I want to trigger $.ajax on form onsubmit and return true only after Ajax return is something valid.

For example:

<form id="myForm" onsubmit="return ajaxValidation();">
    <input id="myString" name="myString" type="text" />
    <input type="submit" value="Submit" />
</form>

In Javascript:

function ajaxValidation() {
    $.ajax({
        async: false,
        type: "POST",
        url: "ajax.php",
        data: { myString: $("#myString").val() }
    }).success(function( response ) {
        alert(response); //Got 'ok'
        if (response=="ok") {
            return true; //mark-1
        } else {
            alert("Oh, string is wrong. Form Submit is cancelled.");
        }
    });
    return false; //mark-2
}

When i submit, i got alert ok, but it returned 'false' because it jumped to final return false line.

Why? I can not understand. Actually, it should hit to return true line. (And, even after return true, the function should stop there and just come out of it)

So it is now means, the parent function does NOT wait to the Ajax Return. Instead, it is continuously running down to the end. Any idea why, please. How to make the parent function to be waiting the Ajax?

回答1:

Since AJAX is asynchronous your validation Would work better using a click handler on the submit button.

Following is based on removing the inline onSubmit

$(function() {

    var $form = $('#myForm');

    $form.find('input[type="submit"]').click(function() {
        $.ajax({
           /* async: false,  this is deprecated*/
            type: "POST",
            url: "ajax.php",
            data: {
                myString: $("#myString").val()
            }
        }).success(function(response) {
            alert(response); //Got 'ok'
            if(response == "ok") {
             /*  submit the form*/
                $form.submit();
            } else {
                alert("Oh, string is wrong. Form Submit is cancelled.");
            }
        }); /* prevent default when submit button clicked*/
        return false;

    });
});

回答2:

Return value at mark 1 is for your success function of ajax request, not for your validation function. Therefore even if it returns it returns only from there and not from validation function which is mark 2

来源：https://stackoverflow.com/questions/14541325/form-onsubmit-to-wait-jquery-ajax-return

标签

jquery

ajax

asynchronous

return

onsubmit