Constants with const

Learn how to declare values that never change using the const keyword.

Step 1 of 5

What is const?

Sometimes you have a value that should never change after you set it — the speed of light, the name of your app, or the number of sides on a hexagon. JavaScript gives you the `const` keyword for exactly this purpose. When you declare a variable with `const`, you are telling JavaScript (and anyone reading your code): 'This value is fixed. Do not touch it.'

If any code later tries to reassign a `const` variable, JavaScript will throw an error and stop execution. This is a safety net — it protects important values from being accidentally overwritten.

Think of it this way: const is like a box with a padlock — once you put something in, it stays.
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