# Best Practices to Follow for Client-Side Variables

When working with **client-side variables** in JENTIS, it’s important to follow certain guidelines to ensure **maximum browser compatibility** and proper execution across all environments. Below are some helpful best practices to keep in mind:

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#### Avoid Using `async` in Function Definitions

Functions for client-side variables **must not start with the `async` keyword**. Asynchronous logic is handled differently (e.g., via callbacks), and `async` is not supported in this context.

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#### Stick to ES5 for Maximum Compatibility

To ensure your variable logic runs reliably across all browsers—including older ones—stick to **ES5 JavaScript syntax**.\
Check compatibility at [Can I use](https://caniuse.com/) if you're unsure whether a feature is supported.

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#### Use `var` Instead of `let` or `const`

Always use `var` when declaring variables inside client-side variable functions. While `let` and `const` are common in modern JavaScript, they are **not fully supported in older browsers** that might still be in use.

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#### Avoid `console.log()` for Debugging

Using `console.log()` inside a client-side variable can **disrupt execution** or lead to undesired behavior.\
Instead, use **JavaScript breakpoints** to inspect and debug your variable logic. You can place breakpoints directly in the **JENTIS JavaScript file** via the browser’s developer tools.

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Following these simple practices will help you build **stable, compatible, and performant** client-side variables in JENTIS.