@blueprintjs/core
Version:
Core styles & components
206 lines • 7.3 kB
JavaScript
/*
* Copyright 2015 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 { CLAMP_MIN_MAX } from "./errors";
export * from "./utils/compareUtils";
export * from "./utils/safeInvokeMember";
/** Returns whether `process.env.NODE_ENV` exists and equals `env`. */
export function isNodeEnv(env) {
return typeof process !== "undefined" && process.env && process.env.NODE_ENV === env;
}
/** Returns whether the value is a function. Acts as a type guard. */
// tslint:disable-next-line:ban-types
export function isFunction(value) {
return typeof value === "function";
}
/**
* 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, skipArray = false) {
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)))));
}
/**
* Converts a React node to an element: non-empty string or number or
* `React.Fragment` (React 16.3+) is wrapped in given tag name; empty strings
* and booleans are discarded.
*/
export function ensureElement(child, tagName = "span") {
if (child == null || typeof child === "boolean") {
return undefined;
}
else if (typeof child === "string") {
// cull whitespace strings
return child.trim().length > 0 ? React.createElement(tagName, {}, child) : undefined;
}
else if (typeof child === "number" || typeof child.type === "symbol" || Array.isArray(child)) {
// React.Fragment has a symbol type, ReactNodeArray extends from Array
return React.createElement(tagName, {}, child);
}
else if (isReactElement(child)) {
return child;
}
else {
// child is inferred as {}
return undefined;
}
}
export function isReactElement(child) {
return (typeof child === "object" &&
typeof child.type !== "undefined" &&
typeof child.props !== "undefined");
}
export function getDisplayName(ComponentClass) {
return ComponentClass.displayName || ComponentClass.name || "Unknown";
}
/**
* 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
*/
export function isElementOfType(element, ComponentType) {
return (element != null &&
element.type != null &&
element.type.displayName != null &&
element.type.displayName === ComponentType.displayName);
}
// tslint:disable-next-line:ban-types
export function safeInvoke(func, ...args) {
if (isFunction(func)) {
return func(...args);
}
return undefined;
}
// tslint:disable-next-line:ban-types
export function safeInvokeOrValue(funcOrValue, ...args) {
return isFunction(funcOrValue) ? funcOrValue(...args) : funcOrValue;
}
export function elementIsOrContains(element, testElement) {
return element === testElement || element.contains(testElement);
}
/**
* Returns the difference in length between two arrays. A `null` argument is
* considered an empty list. The return value will be positive if `a` is longer
* than `b`, negative if the opposite is true, and zero if their lengths are
* equal.
*/
export function arrayLengthCompare(a = [], b = []) {
return a.length - b.length;
}
/**
* Returns true if the two numbers are within the given tolerance of each other.
* This is useful to correct for floating point precision issues, less useful
* for integers.
*/
export function approxEqual(a, b, tolerance = 0.00001) {
return Math.abs(a - b) <= tolerance;
}
/**
* Clamps the given number between min and max values. Returns value if within
* range, or closest bound.
*/
export function clamp(val, min, max) {
if (val == null) {
return val;
}
if (max < min) {
throw new Error(CLAMP_MIN_MAX);
}
return Math.min(Math.max(val, min), max);
}
/** Returns the number of decimal places in the given number. */
export function countDecimalPlaces(num) {
if (!isFinite(num)) {
return 0;
}
let e = 1, p = 0;
while (Math.round(num * e) / e !== num) {
e *= 10;
p++;
}
return p;
}
/**
* Throttle an event on an EventTarget by wrapping it in a
* `requestAnimationFrame` call. Returns the event handler that was bound to
* given eventName so you can clean up after yourself.
* @see https://developer.mozilla.org/en-US/docs/Web/Events/scroll
*/
export function throttleEvent(target, eventName, newEventName) {
const throttledFunc = _throttleHelper((event) => {
target.dispatchEvent(new CustomEvent(newEventName, event));
});
target.addEventListener(eventName, throttledFunc);
return throttledFunc;
}
/**
* Throttle a callback by wrapping it in a `requestAnimationFrame` call. Returns
* the throttled function.
* @see https://www.html5rocks.com/en/tutorials/speed/animations/
*/
export function throttleReactEventCallback(callback, options = {}) {
const throttledFunc = _throttleHelper(callback, (event2) => {
if (options.preventDefault) {
event2.preventDefault();
}
},
// prevent React from reclaiming the event object before we reference it
(event2) => event2.persist());
return throttledFunc;
}
/**
* Throttle a method by wrapping it in a `requestAnimationFrame` call. Returns
* the throttled function.
*/
// tslint:disable-next-line:ban-types
export function throttle(method) {
return _throttleHelper(method);
}
// tslint:disable-next-line:ban-types
function _throttleHelper(onAnimationFrameRequested, onBeforeIsRunningCheck, onAfterIsRunningCheck) {
let isRunning = false;
const func = (...args) => {
// don't use safeInvoke, because we might have more than its max number
// of typed params
if (isFunction(onBeforeIsRunningCheck)) {
onBeforeIsRunningCheck(...args);
}
if (isRunning) {
return;
}
isRunning = true;
if (isFunction(onAfterIsRunningCheck)) {
onAfterIsRunningCheck(...args);
}
requestAnimationFrame(() => {
onAnimationFrameRequested(...args);
isRunning = false;
});
};
return func;
}
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