useComputedDirection

Returns a ref of the reading directionality, or null if the component hasn't been mounted yet.

This composable uses Window.getComputedStyle() to get the computed direction attribute. For example, if the component is wrapped in <div dir="rtl">...</div>, this composable detects that and returns 'rtl'.

Because this method must be run on a rendered DOM element, the composable will return null until the component is mounted. Code using this composable should anticipate this, and check whether the value is null.

Usage

Create a template ref that references the root element of the component. The ref attribute provides a direct reference to the root element and allows us to obtain the detected direction by interacting with the DOM element.

<template>
    <div ref="rootElement"></div>
</template>

Pass the template ref to the composable.

const rootElement = ref(null);
const computedDirection = useComputedDirection( rootElement );

When the component mounts, the computed direction is updated.

Full example

In this example, the component is a Dialog that has a different image for LTR and RTL. The composable is used to determine the reading directionaliy which can be either null, 'ltr', or 'rtl'. Based on the direction, a different image of the computer is displayed.

<template>
    <div ref="rootElement">
        <cdx-button @click="open = true"> Open Dialog </cdx-button>

        <client-only>
            <cdx-dialog
                v-model:open="open"
                title="Save changes"
                close-button-label="Close"
                :primary-action="primaryAction"
                :default-action="defaultAction"
                @primary="onPrimaryAction"
                @default="open = false"
            >
            <!-- bind the image source to a computed property -->
                <img
                    :src="computedImageSrc"
                    alt="image of computer"
                    width="223"
                    height="240"
                />
                <p>Do you want to save your changes?</p>
            </cdx-dialog>
        </client-only>
    </div>
</template>

<script>
import { defineComponent, ref, computed } from 'vue';
import { CdxButton, CdxDialog, useComputedDirection } from '@wikimedia/codex';

export default defineComponent({
    name: 'DialogWithImage',
    components: {
        CdxButton,
        CdxDialog,
    },
    setup() {
        const open = ref(false);

        const primaryAction = {
            label: 'Save',
        actionType: 'progressive',
        };

        const defaultAction = {
            label: 'Cancel',
        };

        function onPrimaryAction() {
            open.value = false;
            console.log('Primary action taken');
        }

        const image = {
            "ltr": 'https://upload.wikimedia.org/wikipedia/commons/1/13/Personal_computer%2C_exploded_4.svg',
            "rtl": 'https://upload.wikimedia.org/wikipedia/commons/d/d3/Personal_computer%2C_exploded.svg',
        };

        const rootElement = ref(null);
        const computedDirection = useComputedDirection(rootElement);
        const computedImageSrc = computed (() => {
            return image[computedDirection.value] || image.ltr;
        });

        return {
            open,
            primaryAction,
            defaultAction,
            onPrimaryAction,
            rootElement,
            computedImageSrc,
        };
    },
});
</script>