? JavaScript const

What is const?

• const declares a block-scoped constant variable.

• The variable must be initialized when declared.

• Its binding cannot be reassigned after initialization.

Basic Example

const PI = 3.14159;console.log(PI);  // 3.14159// Trying to reassign throws an error// PI = 3.14;  // TypeError: Assignment to constant variable.

Important Details

• const means the binding (variable reference) is constant, not the value itself.

• For objects and arrays, you can modify their contents, but cannot reassign the variable.

const arr = [1, 2, 3];arr.push(4);        // Allowedconsole.log(arr);   // [1, 2, 3, 4]// arr = [5, 6];    // Error: Assignment to constant variable.

const vs let vs var

When to Use const

• Use const by default.

• Use let only if the variable value will change.

• Avoid var in modern JS.

Want me to show you examples of scope differences or how to safely use const with objects and arrays?