var data = [{start_date:20180601,end_date:20180701},{start_date:20180801,end_date:20180901},{start_date:20181001,end_date:20181101},{start_date:20181201,end_date:20190101}];
var requests = [];
for (var i = 0; i < data.length; i++) {
(function(i, data) {
requests.push(function() {
jQuery.ajax({
url: 'https://reqres.in/api/users?page=1',
method: 'GET',
success: function(result) {
console.log(i); // 0
requests[i].apply(undefined, []);
}
});
});
console.log(i); //counts up
})(i, data);
};
requests[0].apply(undefined,[]);<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
我想知道，这段代码是怎么来的：
for (var i = 0; i < data.length; i++) {
(function(i, data) {
requests.push(function() {
jQuery.ajax({
url: wpApiSettings.root + 'superdooperendpoint/' + apikey + "/" + data[i].start_date + "/" + data[i].end_date,
method: 'GET',
beforeSend: function(xhr) {
// Set nonce here
xhr.setRequestHeader('X-WP-Nonce', wpApiSettings.nonce);
},
success: function(result) {
success_callback({
start_date: data[i].start_date,
end_date: data[i].end_date,
span: data[i].span,
result: result
});
console.log(i); // 0
requests[i].apply(undefined, []);
}
});
});
console.log(i); //counts up
})(i, data);
};
当我在成功函数中执行第一个console.log()时，它总是0，而不是undefined，但是在成功函数之外，它会在迭代for循环中计数。如何才能让它在success函数中计算？
答案 0 :(得分：1)
以下描绘了originalInputs
并行通话
ivar data = [{start_date:20180601,end_date:20180701},{start_date:20180801,end_date:20180901},{start_date:20181001,end_date:20181101},{start_date:20181201,end_date:20190101}];
var requests = [];
for (var i = 0; i < data.length; i++) {
(function(i, data) {
requests.push(function() {
jQuery.ajax({
url: 'https://reqres.in/api/users?page=1',
method: 'GET',
success: function(result) {
console.log(i);
}
});
});
})(i, data);
};
for (var i = 0; i < requests.length; i++) {
requests[i].apply(undefined, []);
}
顺序通话
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>var data = [{start_date:20180601,end_date:20180701},{start_date:20180801,end_date:20180901},{start_date:20181001,end_date:20181101},{start_date:20181201,end_date:20190101}];
var requests = [];
for (var i = 0; i < data.length; i++) {
(function(i, data) {
requests.push(function() {
jQuery.ajax({
url: 'https://reqres.in/api/users?page=1',
method: 'GET',
success: function(result) {
console.log(i);
i++;
if(i < requests.length) {
requests[i].apply(undefined, []);
}
}
});
});
})(i, data);
};
requests[0].apply(undefined, []);
解释 - 迭代函数时，对于<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>数组中的每个函数，requests的值就像参数一样被传递/存储。当您从外部调用i时，在函数完成时，将绘制requests[0]的存储值，即0。然后，再次触发存储在i的函数，即最终创建无限循环。为了绘制适当的值，循环遍历index = 0数组并逐个调用单个函数以查看正在记录的i的适当值。
答案 1 :(得分：0)
您需要将i分配给嵌套函数的其他局部变量，并将let i = 0;
for (; i < 100; i++) {
((n) => new Promise(
(res, rej) => setTimeout(res, 100)
).then(() => console.log(i,n))
)(i);
}
的定义放在块之外;
class Window(tk.Tk):
x = datetime.today()
y = x.replace(x.second+30 , hour=0, minute=0, second=0, microsecond=0)
delta_t = y - x
secs = delta_t.seconds + 1
sched = BlockingScheduler()
root = tk.Tk()
def reading_APIfile(self):
# getting current time.
print("here is what is in " )
current_time = strftime("%H:%M:%S", gmtime())
# open and read from json file
# threading.Timer(10, self.reading_APIfile()).start()
with open('JSONresponse.json') as a:
json_dict = json.load(a)
# print(current_time)
self.locationDescription = json_dict['locationDescription']
self.location = json_dict['name']
for obj in json_dict['sessions']:
for key in obj:
if obj['stringStartTime'] <= current_time and obj['stringEndTime'] >= current_time:
self.qrCodeToken = obj['token']
self.startTime = obj['stringStartTime']
self.endTime = obj['stringEndTime']
elif obj['stringEndTime'] <= current_time:
self.qrCodeToken = obj['token']
self.startTime = obj['stringStartTime']
self.endTime = obj['stringEndTime']
for x in obj['courses']:
for key1 in x:
self.subject = x['subjectCode'] + " " + x['subject']
self.Name = x['className']
def __init__(self):
# self.gettingAPI()
self.reading_APIfile()
tk.Tk.__init__(self)
self.title("ODUATTAND")
self.geometry('{}x{}'.format(660, 350))
self.attributes('-zoomed', True) # This just maximizes it so we can see the window. It's nothing to do with fullscreen.
#self.frame = Frame(self.tk)
#self.frame.pack()
self.state = False
self.bind("<F11>", self.toggle_fullscreen)
self.bind("<Escape>", self.end_fullscreen)
#Generat Qr code.
big_code = pyqrcode.create(self.qrCodeToken, error='L')
#print(self.qrcodetoken)
big_code.png('code.png', scale=6, module_color=[0, 0, 0, 128], background=[0xff, 0xff, 0xff])
# Main container
# topleft = Frame(self, bg='white')
btm_left = Frame(self, bg='white')
top_right = Frame(self, bg='white')
btm_right = Frame(self, bg='white')
self.grid_rowconfigure(1, weight=1)
self.grid_columnconfigure(0,weight=1)
# old frame setting
for r in range(6):
self.grid_rowconfigure(r, weight=1)
for c in range(5):
self.grid_columnconfigure(c, weight=1)
# x= self.reading_APIfile.subject
# print ("here is X" + x)
#topleft.grid(row = 0, column = 0, rowspan = 4, columnspan = 4, sticky = W+E+N+S)
btm_left.grid(row = 0, column = 0, rowspan = 6, columnspan = 6, sticky = W+E+N+S)
top_right.grid(row = 0, column = 3, rowspan = 4, columnspan = 3,padx=0, sticky = W+E+N+S)
btm_right.grid(row = 2, column = 3, rowspan = 4, columnspan = 3, sticky = W+E+N+S)
btm_right.grid(row=2, column=3, rowspan=4, columnspan=3, sticky=W + E + N + S)
self.label1 = tk.Label(top_right, text= self.subject+ ": "+ self.Name +"\n" + self.location +"\n "+ self.startTime+ " "+ self.endTime)
self.label1.place(x=190,y=45,anchor="center")
self.label1.config(width=300, font=("Arial", 12), bg="white")
# reading the card
self.code = ''
self.label = tk.Label(btm_right, text="PLease swipe your card")
self.label.place(x=150, y=155, anchor="center")
self.label.config(width=200, font=("Arial", 12), bg="white",padx=0)
#if self.code !="":
self.canvas = Canvas(btm_right, width=250, height=200, highlightthickn=0)
self.canvas.place(x=120,y=40, anchor="center")
tk_img = Image.open('check.png')
check_img1=tk_img.resize((150,130), Image.ANTIALIAS)
check_img2=ImageTk.PhotoImage(check_img1)
panel = tk.Label(btm_right, image=check_img2)
panel.image = check_img2
self.x = self.canvas.create_image( 155, 125, image=check_img2)
self.canvas.itemconfigure(self.x, state=tk.HIDDEN)
self.canvas.configure(background='white')
# self.label1.grid(row=2, column=2)
self.bind('<Key>', self.get_key)
#insert QR code
Qrimage = Image.open('code.png')
Qrimage1 = Qrimage.resize((400, 400), Image.ANTIALIAS)
Qrimage2 = ImageTk.PhotoImage(Qrimage1)
# img=img.subsample(2,2)
panel = tk.Label(btm_left, image=Qrimage2)
panel.place(x=200, y=175, anchor="center")
# panel.grid(row=0, column=1, sticky="nw")
panel.image = Qrimage2
# insert a Logo
path = "/home/mohamedshaaban/PycharmProjects/untitled1/986.gif"
image = Image.open('986.gif')
image1 = image.resize((100, 50), Image.ANTIALIAS)
image2 = ImageTk.PhotoImage(image1)
# img=img.subsample(2,2)
panel = tk.Label(btm_right, image=image2)
panel.place(x=160, y=200, anchor="center" )
panel.config(highlightthickness=0)
# panel.grid(row=0, column=1, sticky="nw")
panel.image = image2
top_right.grid_rowconfigure(0, weight=1)
top_right.grid_columnconfigure(1, weight=1)
# self.th = threading.Timer(5.0,self.callinginit)
print("here is what is 222 ")
# self.callinginit()
def callinginit(self):
# self.__init__()
self.reading_APIfile()
print("it is working")
# self.after(150000,self.callinginit())