Unlocking the Power of `const`: A Practical Guide for JavaScript Developers

const PI = 3.14159;  // Constant value for pi
const MAX_SPEED = 100; // Constant speed limit

console.log(PI); // Output: 3.14159
console.log(MAX_SPEED); // Output: 100

Here, PI and MAX_SPEED become constants you can use throughout your code, ensuring their values remain consistent.

Important Note: While the variable itself cannot be reassigned, if the const variable holds an object or an array, you can still modify the properties or elements within it.

1. Accidental Reassignment: Using const helps prevent accidental reassignment to the variable itself, making your code more robust. For example:

   const AGE = 25;
   AGE = 30; // This will throw an error because you cannot reassign `AGE`
   

2. Modifying Object/Array Properties: If you need to modify the contents of an object or array stored in a const variable, you can still do so by accessing and modifying its properties or elements.

   const person = { name: "foo", age: 30 };
   person.age = 35; // This is allowed, modifying the `age` property within the object
   
   const colors = ["red", "green"];
   colors[0] = "blue"; // This is allowed, modifying the first element of the array
   

In summary:

• Use const to declare variables that should not be reassigned.
• Remember, const makes the variable reference, not the value itself, immutable.
• For objects and arrays stored in const variables, you can still modify their internal properties and elements.