wxs

WXS, short for Weixin Script, is a scripting language used in WeChat Mini Programs to implement logic within the template layer. It runs in a secure sandbox separate from the main page script and is designed for data processing, formatting, and simple computations tied to the view.

Origin and scope: Developed by Tencent as part of the WeChat Mini Program ecosystem, WXS provides a restricted subset of JavaScript syntax and a lightweight module system. WXS code is typically stored in .wxs files and loaded into WXML files using a wxs tag with a src attribute; in the template, the loaded module is referenced through a module alias defined by the module attribute.

Usage: A WXS module exports functions and values via module.exports, which are then callable from the template via the module alias. This is commonly used for formatting dates or numbers, localizing strings, or preparing short collections before rendering, keeping the page’s logic separate from UI code.

Limitations: WXS cannot access the DOM, perform network requests, or interact with local storage. It also has a restricted API surface and executes within its own runtime, so WXS code is generally lighter and less capable than the page's JavaScript context. This design aims to improve security and rendering performance by moving certain logic out of the main script.