js 监听是否停留在页面 并修改 页面 title

(function () {
        // 判断用户是否观看当前页面，浏览器兼容
        let state, visibilityChange;
        if (typeof document.hidden !== 'undefined') {
            visibilityChange = 'visibilitychange';
            state = 'visibilityState';
        } else if (typeof document.mozHidden !== 'undefined') {
            visibilityChange = 'mozvisibilitychange';
            state = 'mozVisibilityState';
        } else if (typeof document.msHidden !== 'undefined') {
            visibilityChange = 'msvisibilitychange';
            state = 'msVisibilityState';
        } else if (typeof document.webkitHidden !== 'undefined') {
            visibilityChange = 'webkitvisibilitychange';
            state = 'webkitVisibilityState';
        }
        // 监听用户是否观看当前页面
        const that = this;
        document.addEventListener(visibilityChange, function () {
            if (document[state] === 'hidden') {
                //已离开当前页面
                document.title = "★工具箱★快回来哟~"
            } else if (document[state] === 'visible') {
　　　　//返回了当前页面
                document.title = "工具箱"
            }
        }, false)
    }())