我有一个内部调用 API 的 setInterval 设置。根据 api 响应，我管理 previousState 和 currentState 变量。
我需要确保每个下一个 setInterval 东西都发生在前一个已经由变量更新时。
我该怎么做？
let previous = null;
let current = null;
const fakeApi = () => {
return new Promise((resolve) => setTimeout(resolve(1), 3000));
};
async function fetchData() {
current = await fakeApi();
callB(previous, current);
previous = current;
}
function getStats(cb) {
setInterval(fetchData, 3000);
}
function callB(prev, curr) {
console.log(prev + " >>> " + curr);
}
getStats(callB);回答1
代替 setInterval，您可以创建一个 sleep 函数，然后在完成后调用 fetchData
let previous = null;
let current = null;
const fakeApi = () => {
return new Promise((resolve) => setTimeout(resolve(1), 3000));
};
const sleep = (ms) => new Promise(res => setTimeout(res, ms));
async function fetchData() {
current = await fakeApi();
callB(previous, current);
previous = current;
await sleep(3000);
return fetchData()
}
function callB(prev, curr) {
console.log(prev + " >>> " + curr);
}
getStats(callB);回答2
您可以添加一个 while 循环来重复调用 api 函数：
let previous = null;
let current = null;
const fakeApi = async () => {
return new Promise(resolve => setTimeout(resolve, 3000));
};
let getStats = async ()=>{
while(true) {
await fakeApi()
callB(previous, current);
previous = current;
await new Promise(resolve => setTimeout(resolve, 3000)); //add delay between updates as required
}
})()
function callB(prev, curr) {
console.log(prev + " >>> " + curr);
}
getStats();