js校验浏览器是否支持摄像头及麦克风

window.onload = function () {
        var shower = document.getElementById('show');
        navigator.getUserMedia = navigator.getUserMedia ||
                          navigator.webkitGetUserMedia ||
                          navigator.mozGetUserMedia ||
                          navigator.msGetUserMedia;

        if(navigator.getUserMedia){
            shower.innerHTML = "支持调取摄像头麦克风"
        } else {
            shower.innerHTML = "抱歉不支持"
        }
    }