How Do You Define Constants in JavaScript?

Exploring Constant Declarations in JavaScript

In JavaScript, the ability to designate unchanging variables as constants has been a subject of debate for a significant time. This question explores the options available for defining constants in JavaScript, particularly since the introduction of ES2015.

Is there a dedicated way to define constants in JavaScript?

Prior to ES2015, JavaScript lacked a dedicated keyword for declaring constants. However, with the advent of ES2015 (ES6), a new keyword, const, was introduced for this purpose.

<code class="javascript">const MY_CONSTANT = "some-value";</code>

This declaration effectively defines MY_CONSTANT as a constant, protecting its value from unintended modification. This feature is widely supported across modern browsers and JavaScript environments, including strict mode.

Alternative approaches for legacy support

In scenarios where supporting older browsers or legacy code is a requirement, the var keyword combined with conventions, such as ALL_CAPS, can be employed to indicate the immutability of certain variables:

<code class="javascript">var MY_CONSTANT = "some-value";</code>

Using ALL_CAPS for such variables signals to developers that their values should not be altered during the program's execution. This approach, though not as robust as using const, offers a degree of flexibility for legacy environments.

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