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Lexical Scope

Lexical Scope

Introduction

Lexical scope (also called static scope) means that the scope of a variable is determined by its position in the source code. Inner functions can access variables from outer functions.

Visual Explanation

flowchart TD
    A["Global Scope"]
    B["Outer Function Scope"]
    C["Inner Function Scope"]

    A --> B
    B --> C

    A --> A_Vars["const x = 1"]
    B --> B_Vars["const y = 2"]
    C --> C_Vars["const z = 3"]

    Note["Inner can access: z, y, x"]

Example

const globalVar = 'global';

function outer() {
  const outerVar = 'outer';

  function inner() {
    const innerVar = 'inner';
    console.log(innerVar); // 'inner'
    console.log(outerVar); // 'outer'
    console.log(globalVar); // 'global'
  }

  inner();
}

Summary

Lexical scope is based on code structure, not call stack
Functions can access variables from their containing scopes
It’s “static” — determined at author-time, not runtime

Further Reading

MDN: Scope