JQuery 或 javascript 查找页面的内存使用情况

有没有一种方法可以知道一个网页或者我的 jquery 应用程序使用了多少内存？

我的情况是这样的:

我正在使用 jquery 前端和 restful 后端构建一个数据量很大的 webapp，它们以 JSON 格式提供数据服务。页面加载一次，然后通过 ajax 进行所有操作。

UI 为用户提供了在 UI 中创建多个选项卡的方法，并且每个选项卡可以包含大量的数据。我正在考虑限制它们可以创建的标签的数量，但我认为最好只在内存使用量超过一定阈值时才限制它们。

基于这些答案，我想澄清一下:

  • 我正在寻找一个运行时解决方案(不仅仅是开发人员工具) ，这样我的应用程序就可以根据用户浏览器中的内存使用情况来确定操作。
  • 计算 DOM 元素或文档大小可能是一个很好的估计，但它可能是相当不准确的，因为它不包括事件绑定、数据()、插件和其他内存中的数据结构。
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小开

I don't know of any way that you could actually find out how much memory is being used by the browser, but you might be able to use a heuristic based on the number of elements on the page. Uinsg jQuery, you could do $('*').length and it will give you the count of the number of DOM elements. Honestly, though, it's probably easier just to do some usability testing and come up with a fixed number of tabs to support.

小开

If you want to just see for testing there is a way in Chrome via the developer page to track memory use, but not sure how to do it in javascript directly.

小开

What you might want to do is have the server keep track of their bandwidth for that session (how many bytes of data have been sent to them). When they go over the limit, instead of sending data via ajax, the server should send an error code which javascript will use to tell the user they've used too much data.

小开

You can get the document.documentElement.innerHTML and check its length. It would give you the number of bytes used by your web page.

This may not work in all browsers. So you can enclose all your body elements in a giant div and call innerhtml on that div. Something like <body><div id="giantDiv">...</div></body>

小开

Use the Chrome Heap Snapshot tool

There's also a Firebug tool called MemoryBug but seems it's not very mature yet.

小开

You can use the Navigation Timing API.

Navigation Timing is a JavaScript API for accurately measuring performance on the web. The API provides a simple way to get accurate and detailed timing statistics—natively—for page navigation and load events.

window.performance.memory gives access to JavaScript memory usage data.


Recommended reading

小开

Perfect question timing with me starting on a similar project!

There is no accurate way of monitoring JS memory usage in-app since it would require higher level privileges. As mentioned in comments, checking the number of all elements etc. would be a waste of time since it ignores bound events etc.

This would be an architecture issue if memory leaks manifest or unused elements persist. Making sure that closed tabs' content is deleted completely without lingering event handlers etc. would be perfect; assuming that it's done you could just simulate heavy usage in a browser and extrapolate the results from memory monitoring (type about:memory in the address bar)

Protip: if you open the same page in IE, FF, Safari... and Chrome; and than navigate to about:memory in Chrome, it will report memory usage across all other browsers. Neat!

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最佳答案

2015 Update

Back in 2012 this wasn't possible, if you wanted to support all major browsers in-use. Unfortunately, right now this is still a Chrome only feature (a non-standard extension of window.performance).

window.performance.memory

Browser support: Chrome 6+

2012 Answer

Is there a way to find out how much memory is being used by a web page, or by my jquery application? I'm looking for a runtime solution (not just developer tools), so that my application can determine actions based on memory usage in a user's browser.

The simple but correct answer is no. Not all browsers expose such data to you. And I think you should drop the idea simply because the complexity and inaccuracy of a "handmade" solution may introduce more problem than it solves.

Counting DOM elements or document size might be a good estimation, but it could be quite inaccurate since it wouldn't include event binding, data(), plugins, and other in-memory data structures.

If you really want to stick with your idea you should separate fixed and dynamic content.

Fixed content is not dependant on user actions (memory used by script files, plugins, etc.)
Everything else is considered dynamic and should be your main focus when determining your limit.

But there is no easy way to summarize them. You could implement a tracking system that gathers all these information. All operations should call the appropriate tracking methods. e.g:

Wrap or overwrite jQuery.data method to inform the tracking system about your data allocations.

Wrap html manipulations so that adding or removing content is also tracked (innerHTML.length is the best estimate).

If you keep large in-memory objects they should also be monitored.

As for event binding you should use event delegation and then it could also be considered a somewhat fixed factor.

Another aspect that makes it hard to estimate your memory requirements correctly is that different browsers may allocate memory differently (for Javascript objects and DOM elements).

小开

I would like to suggest an entirely different solution from the other answers, namely to observe the speed of your application and once it drops below defined levels either show tips to the user to close tabs, or disable new tabs from opening. A simple class which provides this kind of information is for example https://github.com/mrdoob/stats.js . Aside of that, it might not be wise for such an intensive application to keep all tabs in memory in the first place. E.g. keeping only the user state (scroll) and loading all the data each time all but the last two tabs are opening might be a safer option.

Lastly, webkit developers have been discussing adding memory information to javascript, but they have gotten in a number of arguments about what and what should not be exposed. Either way, it's not unlikely that this kind of information will be available in a few years (although that information isn't too useful right now).

小开

This question is 5 years old, and both javascript and browsers have evolved incredibly in this time. Since this now possible (in at least some browsers), and this question is the first result when you Google "javascript show memory useage", I thought I'd offer a modern solution.

memory-stats.js: https://github.com/paulirish/memory-stats.js/tree/master

This script (which you can run at any time on any page) will display the current memory useage of the page: 

var script=document.createElement('script');
script.src='https://rawgit.com/paulirish/memory-stats.js/master/bookmarklet.js';
document.head.appendChild(script);


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