Scope in JavaScript refers to context (or portion) of the code which determines the accessibility (visibility) of variables. In JavaScript, we have two types of scope, local , and global.

All JavaScript programming happens in an environment like a web browser, Node, or Bun.js. Each of these environments has its own set of pre-defined variables like window and console.

The JavaScript executes within the larger context of the surrounding code— that’s why you can reference the variables. Now we start to see some of the power that has made JSX so successful.

JavaScript Typing Unlike strongly typed programming languages such as C#, JavaScript is loosely typed and allows you to assign any data type to a variable without giving the variable a specific type.

Chrome also supports using these new custom variables in JavaScript without any issues. CSS variables are very new though have been in the works for years — but they’re not widely supported yet.