angular.js解析整数错误 [英] angular.js parsing integer incorrectly

问题描述

我使用的角度进行一个AJAX调用我自己的REST API。

I'm using angular to make an AJAX call to my own REST API.

$scope.authenticate = function() {
    $http({
        headers: httpHeaders,
        url: '/something/',
        method: "POST",
        data: { 'userId' : $scope.userId, 'password': $scope.password },
        cache: false
    })
    .success(function(response, status) {
        console.log(response);
        var ourstring = JSON.stringify(response);
        console.log(ourstring);
        $scope.authenticate_data = response;
        $scope.sessionId = response.sessionId;
        $scope.cookie = response.cookie;
        $scope.message = "You have successfully authenticated."
    });
}

不知何故，角度不正确地分析整数，并在Chrome督察的网络选项卡，呼叫显示以下内容：

Somehow, angular incorrectly parses integers, and in the Chrome inspector's network tab, the call shows the following:

请求TAB

{的sessionId：115053508782199126，曲奇：JSESSIONID = E61DD3443AE9E119060A637CF039936B;路径= / web服务}

preVIEW TAB（存储在范围内的值）

{的sessionId：115053508782199120，曲奇：JSESSIONID = E61DD3443AE9E119060A637CF039936B;路径= / web服务}

当我包裹整数作为在后端的字符串，一切都很好。但是，我真的很想知道是什么原因造成这个错误。

When I wrap the integer as a string in the backend, everything is fine. However, I really want to get understand what is causing this error.

相关链接：<一个href=\"http://stackoverflow.com/questions/22696395/angular-resource-does-not-parse-correctly-an-integer-response\">Angular $资源不能正确分析

推荐答案

相反，我们所拥有的编号 s，它被存储为的 IEEE754浮点值。而从 ECMAScript标准，我们有：

There is no such thing as a purely integer variable in JavaScript.

Instead, all we have are Numbers, which are stored as IEEE754 floating-point values. And from the ECMAScript standard, we have:

请注意，所有的正和负整数，其量值不大于2 ^ 53是在数字型再presentable（的确，整数0具有两个重presentations，+ 0和-0）

Note that all the positive and negative integers whose magnitude is no greater than 2^53 are representable in the Number type (indeed, the integer 0 has two representations, +0 and −0).

请注意，这样做的不的意思是在JavaScript中重新presentable的最大整数是2 ^ 53，而一旦你得到比这个更大的，只有一些整数可以重新presented。一旦你已经用尽了IEEE754浮点重新presentation的53位尾数，也开始出现在整数之间的差距。

Note that this does not mean that the largest integer representable in JavaScript is 2^53, but rather that once you get larger than this, only some integers can be represented. Once you've exhausted the 53-bit mantissa of the IEEE754 floating point representation, there start to appear gaps between the integers.

您例如会话ID 115053508782199126 是相当大于 2 ^ 53 ，和原来的最接近的整数浮点 - 点值是 115053508782199120 。所以，你需要使用字符串。

Your example session ID 115053508782199126 is rather larger than 2^53, and it turns out the closest integer floating-point value to it is 115053508782199120. So, you need to use strings.

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