我试图从谷歌地图API获取一些JSON数据。当我调用此函数时,我想要"测试"变量变为45.但它仍然是0.
以下代码看起来有点愚蠢,因为我想简化一些事情。我有一个有效的API密钥请不要质疑。我误解了Javascript或fetch api还是什么?请帮忙..非常感谢!
### Subset df2, select the city of interest
df3 <- df2 %>%
# In this example, assuming that City 2 and City 3 are of interest
filter(City %in% c(2, 3))
### Plot the data
ggplot(data = df2, aes(x = Year, y = Value, group = factor(City))) +
# Plot all city data here in gray lines
geom_line(size = 1, color = "gray") +
# Plot target city data with colors
geom_line(data = df3,
aes(x = Year, y = Value, group = City, color = factor(City)),
size = 2)
答案 0 :(得分:0)
fetch api返回一个Promise。这是一个异步过程,因此您需要在此处更新test
的值:
then(function(data){ // here })