利用JS调取电脑摄像头，实现拍照功能

1.调取电脑摄像头非常简单，看代码一幕了然

		window.addEventListener("DOMContentLoaded", function() {
			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);
			};
			if(navigator.getUserMedia) { // Standarda
				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);
			}
			else if(navigator.mozGetUserMedia) { // Firefox-prefixed
				navigator.mozGetUserMedia(videoObj, function(stream){
					video.src = window.URL.createObjectURL(stream);
					video.play();
				}, errBack);
			}
			document.getElementById("snap").addEventListener("click", function() {
				context.drawImage(video, 0, 0, 640, 480);
			});
		}, false);

　　可以自己去试试，可能还会有点兼容性问题。