getblog()从数据库中提取博客。
let getBlog = () => {
let blogContent = {};
let command = "select * from informations;";
database.query(command, (err, results) => {
if (err) console.log(err);
for (let totalResults = 0; totalResults < results.length; totalResults++) {
let newObjectForSending = {
id: results[totalResults].id,
title: results[totalResults].title,
description: results[totalResults].description,
likes: results[totalResults].likes,
};
blogContent[totalResults] = newObjectForSending;
}
console.log(blogContent);
/*
here blogContent shows
{
"id":1,
"title":"this is title",
"description":"This is best description",
likes:"300"
}
*/
});
console.log(blogContent);
/*
here blogContent shows
{ }
*/
return blogContent;
};
为什么这里的blogContent在函数的上下文中是全局的，而我们正在内部更改它，所以它应该返回值，有人能解释为什么会这样吗？
有没有不使用promise/async/await的方法>>>有人给了我答案
我如何从异步调用返回响应？
但这一点我不知道，最主要的是我不知道Ajax。
首先，让我们创建一个异步执行程序
// It take 2 args, 1st is time in milliseconds, 2nd is callback function which return "Results"
function delayCallback(ms, fn) {
setTimeout(fn, ms, "Results");
}
delaycallback是通过事件循环执行I/O,这意味着执行需要时间...
null
function delayCallback(time, fn) {
setTimeout(fn, time, "Results");
}
console.log("Executing callback");
console.time("Callback executed...");
delayCallback(1000, () => {
console.timeEnd("Callback executed...");
});
console.log("Hello World");