Lokalise styled components

Project Purpose

This project acts as abstraction for React component styling in Lokalise org.

Currently, we're just proxying styled-components lib with additional helpers.

Styled components

Library exposes styled, css, createGlobalStyle and keyframes helpers from styled-components.

Helpers

On top of basic API, we also expose higher level abstractions like modifier and variants.

To enable declarative reference to theme, we expose generateHelpers function that generates theme helpers to be used in css and styled based on your theme.

generateHelpers

generateHelpers(theme: YourTheme, config?: { spacingName?: 'spacing', objectKeys?: string[] }): Record<keyof YourTheme, Helper>

generateHelpers generates declarative helper functions based on your theme that allow you referencing values from theme without referencing theme directly. This is useful when you want your theme to be dynamic and provided by context (to switch light / dark themes, for example).

const {
	colors: color,
	spacing,
	typography,
} = generateHelpers(
	{
		color: { background: { primary: "gray" } },
		spacing: { 0: "0", 1: "4px" },
		typography: {
			default: {
				fontSize: "16px",
				lineHeight: "20px",
			},
		},
	},
	{ objectKeys: ["typography"] },
);

const Description = styled.p`
	${typography("default")};
	color: ${color("background.primary")};
	padding: ${spacing(1, 0)};
`;

spacing key (configurable in config under spacingKey and defaults to spacing) is a special key that constructs function that accepts 1-4 arguments and concatenates results allowing to provide up to for spacing factors in one call.

By default, exposed functions have typed inputs (path) that are constructed only for scalar values. In the example above, color('background') is not a valid path as it references object, not scalar (string) value. But in cases you want to enable paths for objects, for example for typography above, you need to provide objectKeys config value with relevant theme keys.

Special helpers

There are also some special helpers that are not generated based on theme, but are available in generated helpers.

breakpoints (breakpoints.min(breakpoint: string) => string and breakpoints.max(breakpoint: string) => string) are helpers that allow you to reference breakpoints from theme with min / max syntax.

const { breakpoints } = generateHelpers({
	breakpoints: {
		sm: "480px",
		md: "920px",
	},
});

const Tile = styled.article`
	font-size: 10px;
	${breakpoints.min("sm")} {
		font-size: 12px;
	}
`;

value (value(path: string) => string) is a helper that allows you to reference any value from theme

const { value } = generateHelpers(
	{
		typography: {
			default: {
				fontSize: "16px",
				lineHeight: "20px",
			},
		},
	},
	{ objectKeys: ["typography"] },
);

const Section = styled.section`
	padding: calc(${value("typography.default.lineHeight")} / 2);
`;

valueFromProp (valueFromProp(prop: string, path: string, fallback?: string) => string) is a helper that allows you to reference any value from theme based on prop value

const { valueFromProp } = generateHelpers({
	color: { background: { primary: "gray", secondary: "black" } },
});

const Section = styled.section`
	color: ${valueFromProp("textColor", "color.background")};
	// Or, if you want, you can provide fallback value in which case prop is not required
	color: ${valueFromProp("textColor", "color.background", "primary")};
`;

modifier

modifier(prop: string | (props) => boolean, css: CssDeclaration)

modifier allows us to specify a set of styles based on a boolean prop. Perfect for disabled, checked use cases.

• prop | string / (props) => boolean: Name of the property being checked, or function that accepts all props and returns boolean for more complex decisions.
• css | CssDeclaration: The style that should be applied when value of prop is true-ish (loose check). Return value from css function. May use other theme helpers.

Usage example using styled-components:

import { css, styled, modifier } from '@lokalise/styled';
import { color } from '../my-theme-helpers';

interface ExampleProps {
    $checked?: boolean;
    $disabled?: boolean;
}

const Example = styled.div<ExampleProps>`
    color: ${color('default')}

    ${modifier(
        '$checked',
        css`
            color: ${color('primaryText')}
        `,
    )}
    ${modifier(
        ({ $checked, $disabled }: ExampleProps) => $checked && $disabled,
        css`
            color: ${color('checkedDisabled')}
        `,
    )}
`;

<Example /> // Will render with "default" color
<Example $checked /> // Will render with "primaryText" color
<Example $checked $disabled /> // Will render with "checkedDisabled" color

variants

variants(prop: string | (props) => string, variantsMap: Record<string, CssDeclaration>, defaultVariant: string)

variant enables a "switch" type of behavior where we want to apply a set of styles based on a prop. Great for cases like variant etc.

• prop | string / (props) => string: Name of the property being checked. You may also provide function that returns variant name (key from variants prop) or undefined.
• variantsMap | Record<string, CssDeclaration> An object with variants as keys and result of css as value.
• defaultVariant | string: The variant used when prop value is not provided. Providing default means prop is optional. Leaving default out means prop is required.

Usage examples using styled-components:

import { css, styled, variants } from '@lokalise/styled';
import { color } from '../my-theme-helpers';

interface ExampleProps {
    $variant?: 'primary' | 'secondary' | 'default';
}

const Example = styled.div<ExampleProps>`
    ${variants(
        '$variant',
        {
            primary: css`
                color: ${color('primaryText')}
            `,
            secondary: css`
                color: ${color('secondaryText')}
            `,
            default: css`
                color: ${color('black')}
            `,
        },
        'default'
)};
`;

<Example $variant="primary" /> // Will render with "primaryText" color
<Example /> // Will render with "black" color

import { css, styled, variants } from '@lokalise/styled';
import { color } from '../my-theme-helpers';

interface ExampleProps {
    $progress: number;
}

const Example = styled.div<ExampleProps>`
    ${variants(
        ({ $progress }: ExampleProps) => $progress >= 90 ? 'done' : 'pending',
        {
            done: css`
                color: ${color('green')}
            `,
            pending: css`
                color: ${color('orange')}
            `,
        },
)};
`;

<Example $progress={42} /> // Will render with "orange" color
<Example $progress={99} /> // Will render with "green" color

excludeProps

excludeProps(props: string[])

Generally, you should use props prefixed with $ to indicate that the given prop should not be passed to DOM.

In case you can't do that, excludeProps can be used to make it easier to exclude props using styled-components shouldForwardProp. We should always do this when using custom props.

import { css, styled, excludeProps, modifier } from "@lokalise/styled";

const Example = styled.div.withConfig<{ active?: boolean }>({
	shouldForwardProp: excludeProps(["active"]),
})`
	${modifier("active", css`...`)};
`;

License

This project is APACHE, VERSION 2.0 licensed, see LICENSE.md for details.

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