@blueprintjs/table
Version:
Scalable interactive table component
92 lines • 3.07 kB
JavaScript
;
/*
* Copyright 2017 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.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.requestIdleCallback = void 0;
/**
* Event name for `postMessage`
*/
var MESSAGE_EVENT_DATA = "blueprint-table-post-message";
/**
* Object that holds state for managing idle callbacks
*/
var IDLE_STATE = {
callbacks: [],
triggered: false,
};
var handleIdle = function (event) {
if (event.source !== window || event.data !== MESSAGE_EVENT_DATA) {
return;
}
IDLE_STATE.triggered = false;
var callback = null;
if (IDLE_STATE.callbacks.length > 0) {
callback = IDLE_STATE.callbacks.shift();
}
if (IDLE_STATE.callbacks.length > 0) {
triggerIdleFrame();
}
// finally, invoke the callback. exceptions will be propagated
if (callback) {
callback();
}
};
// check for window since we might be in a headless server environment
if (typeof window !== "undefined") {
if (window.addEventListener != null) {
window.addEventListener("message", handleIdle, false);
}
}
var triggerIdleFrame = function () {
if (IDLE_STATE.triggered) {
return;
}
IDLE_STATE.triggered = true;
/**
* This is the magic that will wait for the browser to be "idle" before
* invoking the callback.
*
* First, we use nested calls to `requestAnimationFrame` which will cause
* the inner callback to be invoked on the NEXT FRAME.
*
* Then, we call to `postMessage` to invoke the `handleIdle` method only
* once the current stack frame is empty.
*
* With this approach, the idle callback will be invoked at most once per
* frame and only after the stack frame is empty.
*/
requestAnimationFrame(function () {
requestAnimationFrame(function () {
postMessage(MESSAGE_EVENT_DATA, "*");
});
});
};
/**
* Invokes the provided callback on the next available frame after the stack
* frame is empty.
*
* At most one callback per frame is invoked, and the callback may be delayed
* multiple frames until the page is idle.
*
* TODO: return a token from this method that allows you to cancel the callback
* (otherwise the callback list may increase without bound).
*/
var requestIdleCallback = function (callback) {
IDLE_STATE.callbacks.push(callback);
triggerIdleFrame();
};
exports.requestIdleCallback = requestIdleCallback;
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