React When->Then

Are you tired of using inline JavaScript expression inside your JSX? Does it make the code unreadable? Have you ever though to yourself "there's got to be a better way"?

Includes TypeScript definitions

Quick Start

npm install --save react-when-then

Simple pattern

<Case when={/* when */}>{/* then */}</Case>

Usable as standalone

import { Case } from 'react-when-then';

export const LoadingIndicator = (props) => (
    <Case when={props.loading}>
        <Loader/>
    </Case>
);

Or inside larger statements

import { Switch, Case, Default } from 'react-when-them';

export const UserProfile = (props) => {
    return (
        <Switch>
            <Case when={props.age < 18}>
                <p>Underaged!</p>
            </Case>
            <Case when={props.age <= 21}>
                <p>Young adult!</p>
            </Case>
            <Default>
                <p>Adult!</p>
            </Default>
        </Switch>
    );
}

Components

When->Then is made of three components: Switch, Case, Default.

Case

Case works as an if statement. Cases can be used by themselves or in combination.

    <Case when={/* Conition /*}>
        {/* Then */}
    </Case>

When used standalone they might be used as:

    export const MyComponent = (props) => (
        <div>
            <Case when={props.warning}>
                // show warning
            </Case>
            <div>
                // rest of the page
            </div>
        </div>
    );

Using multiple standalone Cases can be interpreted as if() {} if() {} if() {}

    if (first) { return /* First */ }
    <Case when={first}>
        // First
    </Case>
    if (second) { return /* Second*/ }
    <Case when={second}>
        // Second
    </Case>

TypeScript generic arguments

Name	Required	Default	Description
ConditionValue	false	boolean	When used with Switch, the type of the when is shared with Switch's condition

Props

Name	Type	Required	Default	Description
when	ConditionValue or any	true	N/A	When used standalone, truthfulness is asserted by ternal when ? then : null. When used with Switch truthfulness is asserted by the Switch's condition.

Switch

Multiple Cases might be wrapped by a Switch. This construction can either be interpreted as switch case default statement of if else statement. Switch iterates through all Cases. First Case resolved as turthy is returned. When no Case is resolved as truthy the Default is returned instead (if specified).

If Else

<Switch>
    // if (first && second){ return /* First then */ }
    <Case when={first && second}>
        // First then
    </Case>
    // else if (second) { return /* Second then */ }
    <Case when={second}>
        // Second then
    </Case>
    // else { return /* Default */ }
    <Default>
        // Default
    </Default>
</Switch>

Switch Case Default

<Switch condition={user.role}>
    <Case when={UserRoles.Admin}>
        <Redirect to={Rotes.AdminHub}/>
    </Case>
    <Case when={UserRoles.User}>
        <Redirect to={Rotes.UserDashboard}/>
    </Case>
    <Default>
        <Redirect to={Routes.Unauthorized}/>
    </Default>
</Switch>

TypeScript generic arguments

Name	Required	Default	Description
ConditionValue	false	boolean	Specifies tye of the condition

Props

Name	Type	Required	Default	Description
condition	ConditionValue or any	false	true	When unspecified the Cases will be tested against true. When specified Cases will be tested by ===
loose	boolean	false	false	Changes assertion from === to ==. Will make condition "" hit 0 etc...
booleanify	boolean	false	false	Will test condition and cases as !!condition == !!when. Usefull when testing for presence of a value as !!{} == !!true in <Case when={data}>

Default

Specifies default fallback for the Switch when no Cases are truthy. Can be specified only once per switch. Doesn't have to be specified at all.

Has neither props nor any generic arguments.

    <Default>
        // Default fallback inside Switch
    </Default>