什么是为了观察去`dataLayer`阵列使用谷歌代码管理模式？ [英] What is the pattern used by Google Tag Manager in order to observe de `dataLayer` Array?

问题描述

我观察到的数据层数组，我看不到推的任何更改。根本没有自定义方法，其实。 GTM如何观察更改阵列？据我所知，变为一个阵列不要扔任何事件，不是吗？

I observed the dataLayer array and I don't see any changes to push. No custom methods at all, actually. How is GTM observing the changes to the array? As far as I know, changes to an Array don't throw any events, do they?

我做了一些调查研究，发现谷歌的库与数据层交互：的 https://github.com/google/data-layer-helper#listening-for-messages 结果
我会看看在code和甚至回答我的问题，如果我理解ineer运作。

I did some more research and found Google's library for interacting with the dataLayer: https://github.com/google/data-layer-helper#listening-for-messages
I'll take a look at the code and maybe even answer my own question if I understand the ineer workings.

推荐答案

由GTM使用的模式是发布 / 用户

Pattern used by GTM is publish / subscriber

在code，有助于识别它的一些细节：线76和的 https://github.com/google/data-layer-helper/blob/master/src/helper/helper.js

Some details in code that helps to recognize it: line 76 and 181 of the https://github.com/google/data-layer-helper/blob/master/src/helper/helper.js

最后行114和119

And finally line 114 and 119

// Add listener for future state changes.
  var oldPush = dataLayer.push;
  var that = this;
  dataLayer.push = function() {
    var states = [].slice.call(arguments, 0);
    var result = oldPush.apply(dataLayer, states);
    that.processStates_(states);
    return result;
  };

看一看到状态变量，它是如何传递给 this.processStates _（）

Take a look into states variable and how it is passed to this.processStates_()

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