你可能不知道的5個強大的HTML5 API
作者:佚名
HTML5提供了一些非常強大的JavaScript和HTML API,來幫助開發者構建精彩的桌面和移動應用程序。本文將介紹5個新型的API,希望對你的開發工作有所幫助
1. 全屏API(Fullscreen API)
該API允許開發者以編程方式將Web應用程序全屏運行,使Web應用程序更像本地應用程序。
- // 找到適合瀏覽器的全屏方法
- function launchFullScreen(element) {
- if(element.requestFullScreen) {
- element.requestFullScreen();
- } else if(element.mozRequestFullScreen) {
- element.mozRequestFullScreen();
- } else if(element.webkitRequestFullScreen) {
- element.webkitRequestFullScreen();
- }
- }
- // 啟動全屏模式
- launchFullScreen(document.documentElement); // the whole page
- launchFullScreen(document.getElementById("videoElement")); // any individual element
2. 頁面可見性API(Page Visibility API)
該API可以用來檢測頁面對于用戶的可見性,即返回用戶當前瀏覽的頁面或標簽的狀態變化。
- // 設置隱藏屬性和可見改變事件的名稱,屬性需要加瀏覽器前綴
- // since some browsers only offer vendor-prefixed support
- var hidden, state, visibilityChange;
- if (typeof document.hidden !== "undefined") {
- hidden = "hidden";
- visibilityChange = "visibilitychange";
- state = "visibilityState";
- } else if (typeof document.mozHidden !== "undefined") {
- hidden = "mozHidden";
- visibilityChange = "mozvisibilitychange";
- state = "mozVisibilityState";
- } else if (typeof document.msHidden !== "undefined") {
- hidden = "msHidden";
- visibilityChange = "msvisibilitychange";
- state = "msVisibilityState";
- } else if (typeof document.webkitHidden !== "undefined") {
- hidden = "webkitHidden";
- visibilityChange = "webkitvisibilitychange";
- state = "webkitVisibilityState";
- }
- // 添加一個標題改變的監聽器
- document.addEventListener(visibilityChange, function(e) {
- // 開始或停止狀態處理
- }, false);
3. getUserMedia API
該API允許Web應用程序訪問攝像頭和麥克風,而無需使用插件。
- // 設置事件監聽器
- window.addEventListener("DOMContentLoaded", function() {
- // 獲取元素
- var canvas = document.getElementById("canvas"),
- context = canvas.getContext("2d"),
- video = document.getElementById("video"),
- videoObj = { "video": true },
- errBack = function(error) {
- console.log("Video capture error: ", error.code);
- };
- // 設置video監聽器
- if(navigator.getUserMedia) { // Standard
- navigator.getUserMedia(videoObj, function(stream) {
- video.src = stream;
- video.play();
- }, errBack);
- } else if(navigator.webkitGetUserMedia) { // WebKit-prefixed
- navigator.webkitGetUserMedia(videoObj, function(stream){
- video.src = window.webkitURL.createObjectURL(stream);
- video.play();
- }, errBack);
- }
- }, false);
4. 電池API(Battery API)
這是一個針對移動設備應用程序的API,主要用于檢測設備電池信息。
- var battery = navigator.battery || navigator.webkitBattery || navigator.mozBattery;
- // 電池屬性
- console.warn("Battery charging: ", battery.charging); // true
- console.warn("Battery level: ", battery.level); // 0.58
- console.warn("Battery discharging time: ", battery.dischargingTime);
- // 添加事件監聽器
- battery.addEventListener("chargingchange", function(e) {
- console.warn("Battery charge change: ", battery.charging);
- }, false);
5. Link Prefetching
預加載網頁內容,為瀏覽者提供一個平滑的瀏覽體驗。
- <!-- full page -->
- <link rel="prefetch" href="http://davidwalsh.name/css-enhancements-user-experience" />
- <!-- just an image -->
- <link rel="prefetch" href="http://davidwalsh.name/wp-content/themes/walshbook3/images/sprite.png" />
責任編輯:陳四芳
來源:
WEB開發者