canvas打开本机摄像头

(function () {

    var video = document.createElement("video");
    video.autoplay="autoplay";
    document.body.appendChild(video);

    function init() {
        navigator.mediaDevices.getUserMedia({
            audio: false, video: true
        }).then(function (result) {
            video.srcObject = result;
        }).catch(function (error) {
            console.log(error);
        })
    }

    init();
})();