jQuery ajax成功函数的返回值
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return value from ajax success function
提问by user2557992
i am trying to return value from ajax success function. but it is returning nothing.
我正在尝试从 ajax 成功函数返回值。但它什么也没有返回。
JS
JS
function calculate_total_percentage(course_log_id){
var total_percentage = 0;
$.ajax({
url:"teacher_internal_exam_management/get_exams_of_course_log/"+course_log_id,
type: "POST",
dataType: "json",
success: function (exams_of_course_log) {
for (var x = 0; x < exams_of_course_log.length; x++) {
total_percentage += parseInt(exams_of_course_log[x].marks_percentage);
}
alert(total_percentage);
return total_percentage;
}
});
}
if i call like that
如果我这样称呼
alert(calculate_total_percentage(course_log_id));
then showing '61' (due to call alert(total_percentage);) but then showing 'undefined' why? It should show '61' twice? What is the problem?
然后显示'61'（由于调用alert（total_percentage）；）但随后显示'未定义'为什么？它应该显示“61”两次？问题是什么？
回答by Reinstate Monica Cellio
The function doesn't just wait until the ajax call is complete before exiting, so you need a way to handle the return value when it does arrive...
该函数不只是等到 ajax 调用完成后再退出，因此您需要一种方法来处理返回值到达时...
function calculate_total_percentage(course_log_id, callback){
$.ajax({
url:"teacher_internal_exam_management/get_exams_of_course_log/"+course_log_id,
type: "POST",
dataType: "json",
success: function (exams_of_course_log) {
var total_percentage = 0;
for (var x = 0; x < exams_of_course_log.length; x++) {
total_percentage += parseInt(exams_of_course_log[x].marks_percentage);
}
callback(total_percentage);
}
});
}
You can now pass a reference to a callback function which is to be executed after the ajax call succeeds...
您现在可以传递对回调函数的引用，该函数将在 ajax 调用成功后执行...
function calculate_total_percentage_success(total_percentage) {
alert(total_percentage);
}
Now you can call your original function like this...
现在你可以像这样调用你的原始函数......
calculate_total_percentage(id, calculate_total_percentage_success);
