关于script标签非标准type属性含义与作用的技术问询

Awesome question—this is a super common trick you’ll spot on modern websites, so let’s break down exactly what’s going on here:

First off, values like type="02aa3743b2e6c0a724cb116b-text/javascript" are non-standard, custom type values—they’re not recognized by browsers as valid executable script types (unlike the standard text/javascript, which is even optional in modern HTML). Their purpose almost always ties to website resource protection or conditional loading logic, and here’s the breakdown:

• Anti-scraping/automation protection
  This is the most common use case. Generic web crawlers and scrapers are programmed to look for scripts with standard text/javascript types to extract or execute. By adding a random, unique prefix to the type value, sites make these scripts invisible to basic crawlers. Meanwhile, the site’s own legitimate frontend code (usually a separate, standard script) will dynamically replace this custom type with the standard text/javascript later on—so real browsers will still run the code normally, but scrapers get blocked.

• Delayed or conditional script execution
  Browsers only execute scripts with a recognized executable type. A script with this custom type gets treated as a plain DOM node (like a data block) instead of runnable code. Sites use this to hold off on executing certain scripts until a specific condition is met—for example, after the page finishes loading, when a user clicks a button, or when a required resource is ready. Once the condition is satisfied, a small JS snippet updates the script’s type attribute to the standard value, triggering execution.

• Internal resource tagging (rare)
  Occasionally, the random string acts as an internal identifier for the site’s own resource loader. It helps categorize scripts (e.g., third-party analytics, dynamic content rendering, core business logic) so the loader can process each type appropriately. That said, this is far less common than the anti-scraping use case.

The core trick here is leveraging browser behavior: if a script’s type isn’t a known executable MIME type, the browser ignores it until something else tells it to run the code.

内容的提问来源于stack exchange，提问作者kevin mayank