javascript - Webpack - 导出 window.function 失败
问题描述
我是 Webpack 的新手,3 天前我开始使用它来改变我们加载 JavaScript 的方式。
正在运行的 webpack 之前的代码用于实现“著名”的褪色效果(来源 gist.github.com/paulirish/1579671)
window.requestNextAnimationFrame =
(function () {
var originalWebkitRequestAnimationFrame = undefined,
wrapper = undefined,
callback = undefined,
geckoVersion = 0,
userAgent = navigator.userAgent,
index = 0,
self = this;
// Workaround for Chrome 10 bug where Chrome
// does not pass the time to the animation function
if (window.webkitRequestAnimationFrame) {
// Define the wrapper
wrapper = function (time) {
if (time === undefined) {
time = +new Date();
}
self.callback(time);
};
// Make the switch
originalWebkitRequestAnimationFrame = window.webkitRequestAnimationFrame;
window.webkitRequestAnimationFrame = function (callback, element) {
self.callback = callback;
// Browser calls the wrapper and wrapper calls the callback
originalWebkitRequestAnimationFrame(wrapper, element);
}
}
// Workaround for Gecko 2.0, which has a bug in
// mozRequestAnimationFrame() that restricts animations
// to 30-40 fps.
if (window.mozRequestAnimationFrame) {
// Check the Gecko version. Gecko is used by browsers
// other than Firefox. Gecko 2.0 corresponds to
// Firefox 4.0.
index = userAgent.indexOf('rv:');
if (userAgent.indexOf('Gecko') != -1) {
geckoVersion = userAgent.substr(index + 3, 3);
if (geckoVersion === '2.0') {
// Forces the return statement to fall through
// to the setTimeout() function.
window.mozRequestAnimationFrame = undefined;
}
}
}
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (callback, element) {
var start,
finish;
window.setTimeout( function () {
start = +new Date();
callback(start);
finish = +new Date();
self.timeout = 1000 / 60 - (finish - start);
}, self.timeout);
};
}
)
();
// It's then used here in our code here:
loadIcons();
function loadCompanyIcons() {
var elements = document.querySelectorAll('img');
if (!elements) return;
Array.prototype.forEach.call(elements, function(el, i){
var watcher = scrollMonitor.create(el, 2000);
watcher.enterViewport(function() {
var srcToInject = el.getAttribute('data-src');
var src = el.getAttribute('src');
if (src === null && srcToInject!=null) { // do not re-execute for images already with injected src
el.style.opacity = 0;
el.style.display = "block";
el.setAttribute('src',srcToInject);
el.onload = imageFound;
el.onerror = imageNotFound;
function imageFound() {
// progressively show image via opacity variation
(function fade() {
var val = parseFloat(el.style.opacity);
if (!((val += .1) > 1)) {
el.style.opacity = val;
requestNextAnimationFrame(fade);
}
})();
}
}
});
});
}
在基本 js 文件上使用时,它可以完美运行。
当我们尝试迁移到 Webpack 并使用“导出”时,我们碰壁了。我们所做的大多数 Webapckexport
一直在工作,所以我认为这个不起作用,因为它不是标准:
function doSth() {
}
但它始于window.doSth()...
这是我们今天做的失败的事情:
js/helpers/requestAnimationFramePolyfill.js
export window.requestNextAnimationFrame =
(function () {
var originalWebkitRequestAnimationFrame = undefined,
wrapper = undefined,
callback = undefined,
geckoVersion = 0,
userAgent = navigator.userAgent,
index = 0,
self = this;
// Workaround for Chrome 10 bug where Chrome
// does not pass the time to the animation function
if (window.webkitRequestAnimationFrame) {
// Define the wrapper
wrapper = function (time) {
if (time === undefined) {
time = +new Date();
}
self.callback(time);
};
// Make the switch
originalWebkitRequestAnimationFrame = window.webkitRequestAnimationFrame;
window.webkitRequestAnimationFrame = function (callback, element) {
self.callback = callback;
// Browser calls the wrapper and wrapper calls the callback
originalWebkitRequestAnimationFrame(wrapper, element);
}
}
// Workaround for Gecko 2.0, which has a bug in
// mozRequestAnimationFrame() that restricts animations
// to 30-40 fps.
if (window.mozRequestAnimationFrame) {
// Check the Gecko version. Gecko is used by browsers
// other than Firefox. Gecko 2.0 corresponds to
// Firefox 4.0.
index = userAgent.indexOf('rv:');
if (userAgent.indexOf('Gecko') != -1) {
geckoVersion = userAgent.substr(index + 3, 3);
if (geckoVersion === '2.0') {
// Forces the return statement to fall through
// to the setTimeout() function.
window.mozRequestAnimationFrame = undefined;
}
}
}
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (callback, element) {
var start,
finish;
window.setTimeout( function () {
start = +new Date();
callback(start);
finish = +new Date();
self.timeout = 1000 / 60 - (finish - start);
}, self.timeout);
};
}
)
();
// It's then used here in our code here:
loadIcons();
function loadIcons() {
var elements = document.querySelectorAll('img');
if (!elements) return;
Array.prototype.forEach.call(elements, function(el, i){
var watcher = scrollMonitor.create(el, 2000);
watcher.enterViewport(function() {
var srcToInject = el.getAttribute('data-src');
var src = el.getAttribute('src');
if (src === null && srcToInject!=null) { // do not re-execute for images already with injected src
el.style.opacity = 0;
el.style.display = "block";
el.setAttribute('src',srcToInject);
el.onload = imageFound;
el.onerror = imageNotFound;
function imageFound() {
// progressively show image via opacity variation
(function fade() {
var val = parseFloat(el.style.opacity);
if (!((val += .1) > 1)) {
el.style.opacity = val;
requestNextAnimationFrame(fade);
}
})();
}
}
});
});
}
然后我们在 main.js 中做
import {requestNextAnimationFrame} from './helpers/requestAnimationFramePolyfill.js'
loadIcons();
function loadCompanyIcons() {
var elements = document.querySelectorAll('img');
if (!elements) return;
Array.prototype.forEach.call(elements, function(el, i){
var watcher = scrollMonitor.create(el, 2000);
watcher.enterViewport(function() {
var srcToInject = el.getAttribute('data-src');
var src = el.getAttribute('src');
if (src === null && srcToInject!=null) { // do not re-execute for images already with injected src
el.style.opacity = 0;
el.style.display = "block";
el.setAttribute('src',srcToInject);
el.onload = imageFound;
el.onerror = imageNotFound;
function imageFound() {
// progressively show image via opacity variation
(function fade() {
var val = parseFloat(el.style.opacity);
if (!((val += .1) > 1)) {
el.style.opacity = val;
requestNextAnimationFrame(fade);
}
})();
}
}
});
});
}
我们也试过:
import {window.requestNextAnimationFrame} from './helpers/requestAnimationFramePolyfill.js'
但没有任何效果,我们知道这一点,因为应该使用 requestAnimationFramePolyfill.js 逐渐淡入 1.0 不透明度的图标,保持 0.1 不透明度。
我不确定这是否是原因。过去一天我无法理解。
解决方案
您正在尝试将功能添加到window
对象中,然后在其他地方使用它。这是使其他文件可以访问函数的一种方法,但是使用 ES6 和 webpack,您可以通过其他方式进行操作。
我建议不要使用变量window
,因为它可能会导致一些window
语法问题。此外,您不再需要向窗口对象添加函数。
这应该适合你。
js/helpers/requestAnimationFramePolyfill.js
const requestNextAnimationFrame = (function { your function });
export { requestNextAnimationFrame };
main.js
import { requestNextAnimationFrame } from './helpers/requestAnimationFramePolyfill.js'
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