async:异步加载脚本,下载完成后立即执行,执行顺序不确定defer:异步加载脚本,在文档解析完成后按顺序执行 1. async特性: - 脚本加载并行于HTML解析 - 下载完成后立即暂停HTML解析并执行脚本 - 多个async脚本执行顺序不可预测 - 适用于不依赖DOM的独立第三方脚本2. defer特性: - 脚本加载同步于HTML解析 - 等到
I know, it's the kind of answer that you'll find everywhere if you ask yourself this question. You need to know that neither async nor defer guarantees non-blocking the rendering as at the end of all, it is up to you and your script. Well, implementing either async or...