Handling constants

What is a constant?

A constant is a data item whose value cannot change during the program’s execution. Thus, as its name implies – the value is constant.

How to handle constants?

A constant that is required in multiple places in the code should be defined by assigning it to a variable at one place. This variable should then be called everywhere the constant is required.

Why do constants need to be handled?

Defining a constant in a single place will help you write clean and readable code.
It will reduce the need to use comments to describe your code.
It will help the project by ensuring that a standard set of constants are used.
If the value of a constant needs to be changed, you need to make a change only where the constant was originally defined, and not everywhere it is being used.

When do constants need to be handled?

When they are required at more than one place in the code.
When they minimize the readability of the code.

Handling constants in ROR:

Ruby constants

A constant that is to be used in the codebase across different files and folders can be defined inside a suitable model to make it globally available.
To define such a constant make sure the variable name is all uppercase. Example:

THUMBNAIL_DIMENSIONS = [50, 50]

Syntax to call the variable-> ModelClassName::VARIABLE_NAME Example:

PhotoBooth::THUMBNAIL_DIMENSIONS

Handling constants in NextJS:

Localization constants

These are meant for locale strings and generally would be in a standalone file called localization.js
As the name suggests it can be used to render it in different languages and have different locale versions for a website.
These can include routes, paths etc.
Example:

export const HTTPS = "https://";

Constants

Design system constants from SCSS. eg: color hexes, screen widths, etc.
Break these down into scoped files under a folder called constants.
These can contain :

Redirects

These are your redirects file required for NextJS routing.
Example:

export const pageNotFoundRedirect = {
	destination: PAGE_NOT_FOUND_ROUTE,
	permanent: false,
}

Persistence, performance, variants, etc.

Handling constants in Angular:

Javascript constants -

Constants can be defined in a constants.ts file which exports each constant individually.
Global constants: Place these constants in the root folder.
Component level constants: Place these in a separate constants file in the component root.
Module level constants: Place these in a separate constants file in the module root.
Example export: export const FOO = 'bar';
Example usage: import { FOO } from '../constants';

Handling SCSS constants:

Constants can be defined in SCSS in a ‘partial’ file, preferably placed in a base-level folder of the directory in which the application’s stylesheets are stored. Example - defining a constant:

$yellow-primary: #FFCC00;

It is recommended to place different categories of variables in separate files and name them accordingly. Example: _fonts.scss, _color_swatches.scss, _mixins.scss
The variables defined in these files can be used in other SCSS files by importing them. Example - import:

@import '../_fonts.scss';

We can also import all the constant containing partials into a ‘global’ SCSS file, which in turn can be imported wherever required.

Handling Constants