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Bootstrap/js/src/dom/polyfill.js

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import EventHandler from './eventHandler'
const Polyfill = (() => {
// defaultPrevented is broken in IE.
// https://connect.microsoft.com/IE/feedback/details/790389/event-defaultprevented-returns-false-after-preventdefault-was-called
const workingDefaultPrevented = (() => {
const e = document.createEvent('CustomEvent')
e.initEvent('Bootstrap', true, true)
e.preventDefault()
return e.defaultPrevented
})()
let defaultPreventedPreservedOnDispatch = true
// CustomEvent polyfill for IE (see: https://mzl.la/2v76Zvn)
if (typeof window.CustomEvent !== 'function') {
window.CustomEvent = (event, params) => {
params = params || {
bubbles: false,
cancelable: false,
detail: null
}
const evt = document.createEvent('CustomEvent')
evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail)
if (!workingDefaultPrevented) {
const origPreventDefault = Event.prototype.preventDefault
evt.preventDefault = () => {
if (!evt.cancelable) {
return
}
origPreventDefault.call(evt)
Object.defineProperty(evt, 'defaultPrevented', {
get() {
return true
},
configurable: true
})
}
}
return evt
}
window.CustomEvent.prototype = window.Event.prototype
} else {
// MSEdge resets defaultPrevented flag upon dispatchEvent call if at least one listener is attached
defaultPreventedPreservedOnDispatch = (() => {
const e = new CustomEvent('Bootstrap', {
cancelable: true
})
const element = document.createElement('div')
element.addEventListener('Bootstrap', () => null)
e.preventDefault()
element.dispatchEvent(e)
return e.defaultPrevented
})()
}
// Event constructor shim
if (!window.Event || typeof window.Event !== 'function') {
const origEvent = window.Event
window.Event = (inType, params) => {
params = params || {}
const e = document.createEvent('Event')
e.initEvent(inType, Boolean(params.bubbles), Boolean(params.cancelable))
return e
}
window.Event.prototype = origEvent.prototype
}
// focusin and focusout polyfill
if (typeof window.onfocusin === 'undefined') {
(() => {
function listenerFocus(event) {
EventHandler.trigger(event.target, 'focusin')
}
function listenerBlur(event) {
EventHandler.trigger(event.target, 'focusout')
}
EventHandler.on(document, 'focus', 'input', listenerFocus)
EventHandler.on(document, 'blur', 'input', listenerBlur)
})()
}
return {
get defaultPreventedPreservedOnDispatch() {
return defaultPreventedPreservedOnDispatch
}
}
})()
export default Polyfill