我有这个功能:
function tryStartLocalTrendsFetch(woeid) {
var userIds = Object.keys(twitClientsMap);
var isStarted = false;
for (var i = 0; i < userIds.length; i++) {
var userId = userIds[i];
var twitClientData = twitClientsMap[userId];
var isWoeidMatch = (woeid === twitClientData.woeid);
if (isWoeidMatch) {
startLocalTrendsFetch(woeid, twitClientData, function (err, data) {
if (err) {
// Couldn't start local trends fetch for userId: and woeid:
isStarted = false;
} else {
isStarted = true;
}
});
// This will not obviously work because startLocalTrendsFetch method is async and will execute immediately
if (isStarted) {
break;
}
}
}
console.log("No users are fetching woeid: " + woeid);
}
这个方法的要点是我想要行 if (isStarted) { break; }
开始工作。原因是,如果它已启动,则不应继续循环并尝试启动另一个循环。
我在 NodeJS 中这样做。
最佳答案
尝试使用递归定义来代替
function tryStartLocalTrendsFetch(woeid) {
var userIds = Object.keys(twitClientsMap);
recursiveDefinition (userIds, woeid);
}
function recursiveDefinition (userIds, woeid, userIndex)
var userId = userIds[userIndex = userIndex || 0];
var twitClientData = twitClientsMap[userId];
var isWoeidMatch = (woeid === twitClientData.woeid);
if (isWoeidMatch && userIndex<userIds.length) {
startLocalTrendsFetch(woeid, twitClientData, function (err, data) {
if (err) {
recursiveDefinition(userIds, woeid, userIndex + 1)
} else {
console.log("No users are fetching woeid: " + woeid);
}
});
} else {
console.log("No users are fetching woeid: " + woeid);
}
}
关于Javascript for循环等待回调,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31028427/