有用於註冊事件處理兩個不同的JavaScript機制:
time.addEventListener("timeupdate", currentTime, true); // W3C DOM Standard
video.ontimeupdate = function() { currentTime() }; // Event handling property
當您使用屬性(ontimeupdate
),你給它一個值,該值將被當您將該屬性設置爲其他值時會被覆蓋。
所以,當你這樣做:
video.ontimeupdate = function() {currentTime()};
它獲取此之後覆蓋:
video.ontimeupdate = function() { progressBarUpdate() };
爲了防止這種情況發生,使用更現代化的W3C DOM Level 2 event handling model使用addEventListener
video.addEventListener("timeupdate", currentTime);
video.addEventListener("timeupdate", progressBarUpdate);
This將把這兩個函數註冊爲timeupdate
事件的回調函數。
此外,對於addEventListener
(一個布爾)表明是否要回調在捕獲階段(true
)或冒泡階段(false
)火了第三個參數。需要捕獲階段(在IE 9之前IE不支持它)很不尋常,因此您可能想要將現有的true
值修改爲false
,或者只是省略第三個參數,因爲false
是默認值。
這裏的工作的例子,實際上顯示了3個事件處理程序都綁到timeupdate
事件(請務必在片段窗口向下滾動才能看到該消息):
var videoElement = null;
var current = null
var duration = null;
var div1, div2;
window.addEventListener("DOMContentLoaded", function(){
// Get DOM References to media element:
videoElement = document.getElementById('bikeSafe');
// ...to video span elements:
current = document.getElementById('current');
duration = document.getElementById('duration');
div1 = document.getElementById("timeUpdate1");
div2 = document.getElementById("timeUpdate2");
// Wire Up Video to use its API:
videoElement.addEventListener("play", setCounter);
videoElement.addEventListener("ended", endVideo);
videoElement.addEventListener("durationchange", updateStatus);
videoElement.addEventListener("timeupdate", setCounter);
videoElement.addEventListener("timeupdate", updateDiv1);
videoElement.addEventListener("timeupdate", updateDiv2);
});
// Video API:
function updateDiv1(){ div1.innerHTML = "Hello from timeupdate event handler!" }
function updateDiv2(){ div2.innerHTML = "Hello from different timeupdate event handler!" }
// Set the value for the current position in the video
function setCounter() {
// This function is wired up to the video element's timeupdate event, which
// fires when the current time value changes.
current.innerHTML = (videoElement.duration - videoElement.currentTime).toFixed(3);
}
function endVideo() {
// Reset video back to beginning when it ends
videoElement.currentTime = 0;
};
function updateStatus() {
// This will fire when the video's durationchange event fires
// and that will happen upon the successful loading of the image
// for the first time when it becomes known how long the duration
// of the video is.
current.innerHTML = videoElement.duration.toFixed(3);
duration.innerHTML = videoElement.duration.toFixed(3);
};
video { width:40%; }
<video id="bikeSafe" width="400" controls>
<source src="http://www.w3schools.com/html/mov_bbb.mp4" type="video/mp4">
<p>Your browser does not support HTML5 video.</p>
</video>
<p>
Time Remaining: <span id="current"></span> |
Total Length: <span id="duration"></span>
</p>
<div id="timeUpdate1"></div>
<div id="timeUpdate2"></div>
使用' video.addEventListener('timeupdate',...)'就像你用'time.addEventListener'和'seek.addEventListener'做的那樣 - 我不確定'time'和'seek'對象是什麼,但代碼看起來像錯誤地以 –