详解Javacript和AngularJS中的Promises

function success(position){
  var cords = position.coords;
  console.log(coords.latitude + coords.longitude);
}

function error(err){
  console.warn(err.code+err.message)
}

navigator.geolocation.getCurrentPosition(success, error);
 

async1(function(){
  async2(function(){
    ...
    asyncN(null, null);
    ...
  }, null)
}, null)
 

var counter = N;
function success(){
  counter--;
  if(counter === 0){
    alert('done');
  }
}

async1(success);
async2(success);
...
asyncN(success);

 

async(function(value){
  myFirstDeferred.resolve(value);
}, function(errorReason){
  myFirstDeferred.reject(errorReason);
})
 

var myFirstPromise = myFirstDeferred.promise;

myFirstPromise
  .then(function(data){
  
  }, function(error){
  
  })
 

var anotherDeferred = $q.defer();

anotherDeferred.promise
  .then(function(data){
  
  },function(error){
  
  })
  
//调用异步方法
async(anotherDeferred.resolve, anotherDeferred.reject);

anotherDeferred.promise
  .then(function(data){
  
  }, function(error){
  
  })
 

function getData(){
  var deferred = $q.defer();
  async(deferred.resolve,deferred.reject);
  return deferred.promise;
}

//deferred的promise属性记录了达到resolved, reject状态所需要执行的success和error方法
var dataPromise = getData();
dataPromise
  .then(function(data){
    console.log('success');
  }, function(error){
    console.log('error');
  })
 

dataPromise
  .then(function(data){
    console.log('success');
  })
 

dataPromise
  .then(null, function(error){
    console.log('error');
  })
  
或

dataPromise.catch(function(error){
  console.log('error');
})
 

var finalCallback = function(){
  console.log('不管回调成功或失败都返回这个结果');
}

function async(value){
  var deferred = $q.defer();
  var result = value / 2;
  deferred.resolve(result);
  return deferred.promise;
}
 

var promise = async(8)
  .then(function(x){
    return x+1;
  })
  .then(function(x){
    return x*2;
  })
  
promise.then(function(x){
  console.log(x);
}) 

function async1(value){
  var deferred = $q.defer();
  var result = value * 2;
  deferred.resolve(result);
  return deferred.promise;
}

function async2(value){
  var deferred = $q.defer();
  var result = value + 1;
  deferred.resolve(result);
  return deferred.promise;
}

var promise = async1(10)
  .then(function(x){
    return async2(x);
  })
  
promise.then(function(x){
  console.log(x);
}) 
 

function logValue(value){
  console.log(value);
}

async1(10)
  .then(async2)
  .then(logValue);
 

async1()
  .then(async2)
  .then(async3)
  .catch(handleReject)
  .finally(freeResources);
 

var promise = async().then(function(value){
  if(true){
    return value;
  } else {
    return $q.reject('value is not satisfied');
  }
})

function getDataFromBackend(query){
  var data = searchInCache(query);
  if(data){
    return $q.when(data);
  } else {
    reutrn makeAasyncBackendCall(query);
  }
}

var allPromise = $q.all([
  async1(),
  async2(),
  ...
  asyncN();
])

allProise.then(function(values){
  var value1 = values[0],
    value2 = values[1],
    ...
    valueN = values[N];
    
  console.log('all done');
})