关于HTML面试题汇总之visibility

const BROWER_PREFIX = ['webkit','moz','ms','o',''];
class Utils{
    constructor(){
      this.isPageVisibilitySupport = false;
      this.prefix = '';
    }
    /**
     * 获取驼峰命名格式的属性名
     * @param prefix {string} 前缀
     * @param value {string} 属性名
    */
    prefixToCamel( prefix, value){
      if(prefix){
        return prefix + value.slice(0,1).toUpperCase() + value.slice(1);
      }
      return value;
    }
    calculatePageVisibilitySupport(){
        var that = this;
        BROWER_PREFIX.forEach(function (data) {
          if(!that.isPageVisibilitySupport && document[that.prefixToCamel(data,'hidden')] != undefined ){
            that.isPageVisibilitySupport = true;
            that.prefix = data;
          }
        });
        return that.isPageVisibilitySupport;
    }
    isHidden(){
        if(this.calculatePageVisibilitySupport()){
            return document[this.prefixToCamel(this.prefix,'hidden')];
        }
        return undefined;
    }
    visibilityState(){
        if(this.calculatePageVisibilitySupport()){
            return document[this.prefixToCamel(this.prefix,"visibilitystate")];
        }
        return undefined;
    }
} 
export default Utils;

import utils from 'src/utils';
var _utils = new utils();
class Core {
    static visibilityChange(callback){
        if( _utils.calculatePageVisibilitySupport() && typeof callback == 'function'){
            return document.addEventListener(Core.prefix + 'visibilitychange',function(event){
                this.hidden = Core.hidden;
                this.visibilityState = Core.visibilityState;
                callback.call(this,event);
            });
            return undefined;
        }
    }
}
Core.hidden = _utils.isHidden();
Core.visibilityState = _utils.visibilityState();
export default Core;