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You either 'let', 'var' or keep 'const' in JavaScript

Lody G Mtui on June 12, 2022

Difference between var, let and const In JavaScript, variables are assigned using three main keywords/ways which are:- var let const....
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Ben Sinclair •

And const can neither be re-declared nor updated.

Const can be updated if it's an object or array. This is fine, for example:

const foo = [];

foo.push("hello");
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So const is kinda-sorta-const, depending where you learned the word "constant". You can't redeclare it or make it point at anything else, but you can modify it if it's a container for other things.

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jzombie •

Const gives you a constant memory reference. You can't reassign the memory reference, but any properties can be [re]assigned. The constant value assumption is only for primitive types.

To freeze objects: developer.mozilla.org/en-US/docs/W...

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Lody G Mtui •

I'll check on this. Thanks for the feedback

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Randall • • Edited

It's not a reference to specific memory. The thing pointed to by a const variable can and often will move locations in memory (for example if you keep pushing onto an array, the engine will eventually have to allocate a new, bigger block of memory for it). It's just a constant reference to a specific value.

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jzombie •

Thanks for the clarification.

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Lody G Mtui •

Thanks for this information, I will learn it and update it

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Steve Knoblock •

The computer science definition of constant existed for forty years or more before JavaScript decided to use the same term for something different than most computer languages and in mathematics.