网络摄像头怎么利用JavaScript进行调用

(function (window, document) {
  window.camera = {
    init: function (options) {
      /**
       * options 属性示例
       * videoID: video控件ID
       * canvasID: canvas控件ID
       * fileID: type为file的input控件的ID
       * imageID: img控件的ID
       * videoEnable: 是否启用摄像头
       * audioEnable: 是否启用麦克风
       * videoWidth: 视频宽度
       * videoHeight: 视频高度
       * photoWidth: 拍照宽度
       * photoHeight: 拍照高度
       */

      _options = options;
      if (isMobileTerminal()) {
        initMobileTerminal();
      } else {
        initComputerTerminal();
      }
    },
    photo: function () {
      if (isMobileTerminal()) {
        photoMobileTerminal();
      } else {
        photoComputerTerminal();
      }
    }
  };

  let _options = null;

  function initComputerTerminal() {
    let videoDom = document.getElementById(_options.videoID);
    if (!videoDom) {
      alert('Video 控件无效');
      return;
    }

    let canvasDom = document.getElementById(_options.canvasID);
    if (!canvasDom) {
      alert('Canvas 控件无效');
      return;
    }
    canvasDom.setAttribute('width', _options.photoWidth + 'px');
    canvasDom.setAttribute('height', _options.photoHeight + 'px');

    let parameters = {
      video: _options.videoEnable ? {
        width: _options.videoWidth,
        height: _options.videoHeight
      } : false,
      audio: _options.audioEnable
    };

    navigator.mediaDevices.getUserMedia(parameters)
      .then(function (MediaStream) {
        video.srcObject = MediaStream;
        video.play();
      }).catch(function (reason) {
        console.log(reason);
        alert(reason);
      });
  }

  function photoComputerTerminal() {
    let videoDom = document.getElementById(_options.videoID);
    if (!videoDom) {
      alert('Video 控件无效');
      return;
    }


    let canvasDom = document.getElementById(_options.canvasID);
    if (!canvasDom) {
      alert('Canvas 控件无效');
      return;
    }

    let context = canvasDom.getContext('2d');
    context.drawImage(videoDom, 0, 0, _options.photoWidth, _options.photoHeight);
  }

  function initMobileTerminal() {
    let fileDom = document.getElementById(_options.fileID);
    if (!fileDom) {
      alert('File 控件无效');
      return;
    }

    fileDom.setAttribute('accept', 'image/*');
    fileDom.setAttribute('capture', 'camera');

    let canvasDom = document.getElementById(_options.canvasID);
    if (!canvasDom) {
      alert('Canvas 控件无效');
      return;
    }

    canvasDom.setAttribute('width', _options.photoWidth + 'px');
    canvasDom.setAttribute('height', _options.photoHeight + 'px');

    let imageDom = document.getElementById(_options.imageID);
    if (!imageDom) {
      alert('Image 控件无效');
      return;
    }

    fileDom.addEventListener('change', function () {
      let file = fileDom.files[0];
      let reader = new FileReader();
      reader.onloadend = function () {
        imageDom.setAttribute('src', reader.result);

        setTimeout(function () {
          let context = canvas.getContext("2d");
          context.drawImage(imageDom, 0, 0, _options.photoWidth, _options.photoHeight);
        }, 300);
      };
      reader.readAsDataURL(file);
    });
  }

  function photoMobileTerminal() {
    let fileDom = document.getElementById(_options.fileID);
    fileDom.click();
  }

  function isMobileTerminal() {
    if (/AppleWebKit.*Mobile/i.test(navigator.userAgent) || /Mobile/.test(navigator.userAgent) || /MIDP|SymbianOS|NOKIA|SAMSUNG|LG|NEC|TCL|Alcatel|BIRD|DBTEL|Dopod|PHILIPS|HAIER|LENOVO|MOT-|Nokia|SonyEricsson|SIE-|Amoi|ZTE/.test(navigator.userAgent))
      return /Android|webOS|iPhone|iPod|BlackBerry/i.test(navigator.userAgent);
    return false;
  }
})(window, document);