在承诺图书馆Q中,您可以按照以下顺序链接承诺：
var items = ['one','two','three'];
var chain = Q();
items.forEach(function (el) {
chain = chain.then(foo(el));
});
return chain;
但是,以下内容不适用于$q：
var items = ['one','three'];
var chain = $q();
items.forEach(function (el) {
chain = chain.then(foo(el));
});
return chain;
只需使用$q.when()函数：
var items = ['one','three'];
var chain = $q.when();
items.forEach(function (el) {
chain = chain.then(foo(el));
});
return chain;
注意：foo必须是工厂,例如
function setTimeoutPromise(ms) {
var defer = $q.defer();
setTimeout(defer.resolve,ms);
return defer.promise;
}
function foo(item,ms) {
return function() {
return setTimeoutPromise(ms).then(function () {
console.log(item);
});
};
}
var items = ['one','three'];
var chain = $q.when();
items.forEach(function (el,i) {
chain = chain.then(foo(el,(items.length - i)*1000));
});
return chain;
