@blueprintjs/core/src/common/utils/reactUtils.ts

Core styles & components

/*
 * Copyright 2020 Palantir Technologies, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import * as React from "react";

import { isEmptyString } from "./jsUtils";

/**
 * Returns true if `node` is null/undefined, false, empty string, or an array
 * composed of those. If `node` is an array, only one level of the array is
 * checked, for performance reasons.
 */
export function isReactNodeEmpty(node?: React.ReactNode, skipArray = false): boolean {
    return (
        node == null ||
        node === "" ||
        node === false ||
        (!skipArray &&
            Array.isArray(node) &&
            // only recurse one level through arrays, for performance
            (node.length === 0 || node.every(n => isReactNodeEmpty(n, true))))
    );
}

/**
 * Returns true if children are a mappable children array
 *
 * @internal
 */
export function isReactChildrenElementOrElements(
    children: React.ReactNode,
): children is React.JSX.Element[] | React.JSX.Element {
    return !isReactNodeEmpty(children, true) && children !== true;
}

/**
 * Converts a React node to an element. Non-empty strings, numbers, and Fragments will be wrapped in given tag name;
 * empty strings and booleans will be discarded.
 *
 * @param child     the React node to convert
 * @param tagName   the HTML tag name to use when a wrapper element is needed
 * @param props     additional props to spread onto the element, if any. If the child is a React element and this argument
 *                  is defined, the child will be cloned and these props will be merged in.
 */
export function ensureElement(
    child: React.ReactNode | undefined,
    tagName: keyof React.JSX.IntrinsicElements = "span",
    props: React.HTMLProps<HTMLElement> = {},
) {
    if (child == null || typeof child === "boolean" || isEmptyString(child)) {
        return undefined;
    } else if (
        typeof child === "string" ||
        typeof child === "number" ||
        isReactFragment(child) ||
        isReactNodeArray(child)
    ) {
        // wrap the child element
        return React.createElement(tagName, props, child);
    } else if (isReactElement(child)) {
        if (Object.keys(props).length > 0) {
            // clone the element and merge props
            return React.cloneElement(child, props);
        } else {
            // nothing to do, it's a valid ReactElement
            return child;
        }
    } else {
        // child is inferred as {}
        return undefined;
    }
}

export function isReactElement<T = any>(child: React.ReactNode): child is React.ReactElement<T> {
    return (
        typeof child === "object" &&
        typeof (child as any).type !== "undefined" &&
        typeof (child as any).props !== "undefined"
    );
}

function isReactFragment(child: React.ReactNode): child is Iterable<React.ReactNode> {
    // bit hacky, but generally works
    return typeof (child as any).type === "symbol";
}

function isReactNodeArray(child: React.ReactNode): child is React.ReactNode[] {
    return Array.isArray(child);
}

/**
 * Returns true if the given JSX element matches the given component type.
 *
 * NOTE: This function only checks equality of `displayName` for performance and
 * to tolerate multiple minor versions of a component being included in one
 * application bundle.
 *
 * @param element JSX element in question
 * @param ComponentType desired component type of element
 */
// eslint-disable-next-line @typescript-eslint/no-empty-object-type
export function isElementOfType<P = {}>(
    element: any,
    ComponentType: React.ComponentType<P>,
): element is React.ReactElement<P> {
    return (
        element != null &&
        element.type != null &&
        element.type.displayName != null &&
        element.type.displayName === ComponentType.displayName
    );
}

export function isReact18OrHigher(): boolean {
    const majorVersion = parseInt(React.version.split(".")[0], 10);
    return majorVersion >= 18;
}