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Detailed explanation and summary of several knowledge points to improve JavaScript performance

黄舟

Mar 09, 2017 pm 02:58 PM

Detailed explanation of several knowledge points to improve JavaScript performance:

I spent some time reading most of the book "High Performance JavaScript" some time ago Books, and then started working on projects. I am glad that the busiest week has passed. Due to lack of time, I didn't write many study notes this month. After the most arduous week, I stayed up late and read the book these two nights... I finally shut down this book when I was still alive...

Now that I have finished reading, I have to learn something. Let me talk about my views on this book first. Overall, the content is good, but it feels a bit old (as a front-end novice, it may be that my own level is limited and I fail to understand the true meaning). In the process of reading this book, I also wrote a lot of code for testing. I also conducted breakpoint tracking on the execution of the writing method advocated in this book and the original popular writing method, so as to understand the problems that can be actually measured. Of course, If you can't see it even if you set a breakpoint and follow the execution, there's nothing you can do about it. Regarding the knowledge points in the book, here is just a brief summary of some of the knowledge points that I personally recommend. Of course~ don’t criticize if you don’t like it.

##For the loading position of js files

In HTML files, the <script> tag can be added to the <head> area and <body&gt ; regional. In view of the single-threaded reason for JavaScript execution and UI rendering, if the js file is loaded, it will block the subsequent parsing process of the page. The page will wait until the js file is fully loaded and run before continuing to perform the operation. Then the problem arises, the page may be blank or stuck. As a front-end developer, it is important not only to realize the requirements, but also to provide a high-quality user experience. Then we need to eliminate the boring waiting of users. To solve this problem, here are two solutions that I have thought of: <p><p>1. <strong>If the js file does not have special requirements, it needs to be rendered on the page. If it has been loaded and compiled before, then choose to place the js file in front of the </script>

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