在添加新数据时删除json数组中的元素? [英] Remove element in json array as new data added?

问题描述

我有一个折线图，随着从MySQL数据库中提取新数据，折线图每5秒更新一次.

I have a line graph that is being updated every 5 seconds as new data is pulled from a mySQL database.

https://gist.github.com/Majella/5fc4cd5f41a6ddf2df23

每次调用数据以停止压缩行/路径时，如何从数组中删除第一个/最旧的元素?

How do I remove the first/oldest element from the array each time the data is called to stop the line/path being compressed?

我试图在调用数据后立即在update函数中添加data.shift()，但仅适用于第一次调用吗?

I've tried adding data.shift() in the update function just after the data is called but only works for the first call?

推荐答案

我不知道getdata.php背后的详细信息，但我认为每次每次返回的数据点都在逐渐增加，因此仅删除了第一个数据点.仍然可以为您提供比所需更大的数据集.因此，您有两种选择:

I don't know the details of what lives behind getdata.php, but I assume it's returning progressively more data points each time, thus removing only the first one still lives you with a larger data set than you want. So you have a couple choices:

1. 更改getdata.php的服务器端，使其仅返回最新的x个数据点(或添加一个querystring参数，以获取多少点/分钟/要检索的内容)

1. Change the server-side of getdata.php to return only the latest x data points (or maybe add a querystring parameter for how many points/minutes/whatever to retrieve)

在updateData中更改客户端以检查数组的长度，并从lengthYouWant减去lengthYouReceived(假设数据已经正确排序)开始对元素进行切片.

Change the client-side in updateData to check the length of the array and .slice off the elements starting at lengthYouWant minus lengthYouReceived (assuming the data is already sorted correctly)

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