function send(obj) {
 if (obj > result.length) return false;
 $http({
    method: "POST",
    url: "url",
    data: postdata,
    timeout: 1000
    })
    .success(function(data) {
       obj++;
       send(obj);
    })
    .error(function(data) {
      
    })
    .finally(function() {
       
    });
}
send(0);

var Request = (i) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
           console.log(i)
           resolve(i+"完成")
        }, 1000)
    })
}
Request(1)
.then((s) => Request(2))
.then((s) => Request(3))
.then((s) => Request(4))

ajax加上参数async: false，改成同步应该就可以了

ajax是异步的，可以使用递归代替循环
在请求成功的回调函数中递归调用请求函数就行了

var result = [1, 2, 3, 4];

httpArray(send, result);

function httpArray(fn, result) {
  var len = result.length;
  exec(fn, len);
  function exec(fn, l) {
    return fn(result[len - l]).then(function () {
      if (l <= 1) return;
      return exec(fn, --l);
    });
  }
}

function send(obj) {
  return $http({
    method: "POST",
    url: "url",
    data: postdata,
    timeout: 1000
  })
    .success(function (data) {

    })
    .error(function (data) {

    })
    .finally(function () {

    });
}