this is a simple demo for getUserMedia.

demo.html

<!--Don't forget to add autoplay attribute-->
<video id="mediaStreamDemo" autoplay></video>

featureDetection.js

navigator.getUserMedia = navigator.getUserMedia ||
    navigator.webkitGetUserMedia ||
    navigator.mozGetUserMedia ||
    navigator.msGetUserMedia;

getUserMedia.js

var constraints =
    {
        video: true,
        audio: true
    };

function success(mediaStream) {
    video = document.getElementById("mediaStreamDemo");
    video.src = window.URL.createObjectURL(mediaStream);
}

function error(e) {
    console.log("error : " + e);
}

navigator.getUserMedia(constraints, success, error);

syntax.js

navigator.getUserMedia ( constraints, successCallback, errorCallback );