判斷瀏覽器是否取得了焦點(diǎn)或者失去焦點(diǎn)，然后動態(tài)修改title

window.onfocus = function () {
  document.title = '你不要我了';
};
window.onblur = function () {
  document.title = '你又回來找我了';
};

// 瀏覽器狀態(tài)
function browser_status(action) {
    // 各種瀏覽器兼容
    let hidden, state, visibilityChange,status
    if (typeof document.hidden !== "undefined") {
        hidden = "hidden"
        visibilityChange = "visibilitychange"
        state = "visibilityState"
    } else if (typeof document.mozHidden !== "undefined") {
        hidden = "mozHidden"
        visibilityChange = "mozvisibilitychange"
        state = "mozVisibilityState"
    } else if (typeof document.msHidden !== "undefined") {
        hidden = "msHidden"
        visibilityChange = "msvisibilitychange"
        state = "msVisibilityState"
    } else if (typeof document.webkitHidden !== "undefined") {
        hidden = "webkitHidden"
        visibilityChange = "webkitvisibilitychange"
        state = "webkitVisibilityState"
    }

    // 添加監(jiān)聽器，在title里顯示狀態(tài)變化
    document.addEventListener(visibilityChange, function() {
        status = document[state]
        if (document[state] == 'hidden') {
            document.title = '你不要我了'
        } else {
            document.title = '你又回來找我了'
        }
    }, false)
}