本来代码是这么写的，在浏览器中运行也是好的。

cc.Class({
    extends: cc.Component,

    properties: {
        _begin: cc.Integer,
    	_end: cc.Integer,
    	_origin: cc.Integer,
    	_camera: cc.Node,
    },

    onLoad () {
        // 找到摄像机
        this.camera = cc.find("Canvas/Main Camera");
        // 开始触摸
	    this.node.on(cc.Node.EventType.TOUCH_START, this.onTouchStart, this);
	    // 触摸中
	    this.node.on(cc.Node.EventType.TOUCH_MOVE, this.onTouchMove, this);
    },

    onTouchStart(event) {
		let touch = event.touch;
		begin = touch.getLocationX();
		origin = this.camera.x;
	},

	onTouchMove(event) {
		let touch = event.touch;
		end = touch.getLocationX();
		dist = parseInt(begin-end);
		this.camera.x = origin + dist;
	},

});

但是构建发布到web之后就失去了触摸反应，打开控制台发现是begin未定义，后面我把那些属性都加上了this，就没有报错了。我想这个原因就在于打包的时候，cocos懂的规则，web不懂才导致的错误。 

cc.Class({
    extends: cc.Component,

    properties: {
        _begin: cc.Integer,
    	_end: cc.Integer,
    	_origin: cc.Integer,
    	_camera: cc.Node,
    },

    onLoad () {
        // 找到摄像机
        this.camera = cc.find("Canvas/Main Camera");
        // 开始触摸
	    this.node.on(cc.Node.EventType.TOUCH_START, this.onTouchStart, this);
	    // 触摸中
	    this.node.on(cc.Node.EventType.TOUCH_MOVE, this.onTouchMove, this);
    },

    start () {

    },

    onTouchStart(event) {
		let touch = event.touch;
		this.begin = touch.getLocationX();
		this.origin = this.camera.x;
        // cc.log("begin: " + begin);
	},

	onTouchMove(event) {
		let touch = event.touch;
		this.end = touch.getLocationX();
		this.dist = parseInt(this.begin-this.end);
		this.camera.x = this.origin + this.dist;
        // cc.log("dist: " + dist);
	},

});

但是！这个效果很生硬，百度说一般用Vector3.Lerp来平滑一下。我捣鼓了半天没弄好，后面改用scrollview组件来装，问题解决。