我想打电话给使用无极这样的谷歌地图地理编码API返回的值:从无极
function makeGeoCodingRequest(address,bounds)
{
/*
Input parameters:
address:a string
bounds: an object of class google.maps.LatLngBounds(southWest,northEast)
This will return a set of locations from the google geocoding library for the given query
*/
var url="https://maps.googleapis.com/maps/api/geocode/json?address=" + address + "&key=AIzaSyD9GBloPC20X-1kWRo7sm_0z5xvCiaSd3c";
var promise,response;
var messages={
"ZERO_RESULTS":"No results were found",
"OVER_QUERY_LIMIT":"We are over the query limit.Wait awhile before making a request",
"REQUEST_DENIED":"Request was denied,probably using a bad or expired API Key",
"INVALID_REQUEST":"Request was sent without the required address,component or component",
"UNKNOWN_ERROR": "There was an error somewhere on Google's servers"
};
if(address)
promise=Q($.ajax({
type: "GET",
url: "https://maps.googleapis.com/maps/api/geocode/json?address=" + address + "&key=API_KEY"
}));
return promise.then(function(data) {
if (data.status === "OK") return data;
else console.error(messages[data.status]);
return null;
});
}
当我调用该函数makeGeoCodingRequest
要求,我发现我得到一个承诺,而不是值:
var geo=makeGeoCodingRequest(address);
console.log(Q.isPromise(geo));//returns true
为什么在返回值之前未执行promise.then?我如何从这个承诺中获得价值而不是另一个承诺?
如果我拒绝使用'promise.then(...)'和'return promise',然后使用'makeGeoCodingRequest(address,bounds).then(...)',它会不会相同? – vamsiampolu 2014-08-27 15:15:49
是的,'makeGeoCodingRequest'返回的promise与''promise.then'处理程序中的返回值具有相同的值。你可以通过返回类似'Q.reject(新错误(“Http请求失败”+ data.status))' – 2014-08-27 15:23:12
谢谢你的答案,一切正常,包括Q.reject。 – vamsiampolu 2014-08-27 15:40:02