![](/img/trans.png)
[英]How to run a funtion onclick of button from one component and funtion run on another compoenent in react native
[英]Implementing another funtion to be run “onSongEnd”
一位好心人帮助我整理了一个剧本,该剧本:
1:从数据库中获取一些数据
2:在屏幕上显示一些信息
3:获取开始歌曲的时间,获取歌曲的持续时间(以秒为单位),并创建一个倒数计时器以刷新页面
数据来自MySql数据库,它基本上是一个历史列表,该列表显示当前正在播放的歌曲以及之前播放的歌曲(元数据包含艺术家,标题,播放的日期,持续时间等内容的概要信息...
现在我的问题是:
当我需要刷新播放列表时,如何添加要运行的功能
现在,我只想向alert("extra function added");
添加一个测试功能alert("extra function added");
添加了alert("extra function added");
我希望每次有新数据的PHP请求时,屏幕都会提醒此消息。
我已经尝试了许多尝试,但是我总是创建函数,然后在代码的错误区域中调用它们,这样我就不会为您带来麻烦。
感谢您的阅读...如果您能提供一些帮助,那将真的帮助我理解正确的程序。
这是脚本。
var PlayList = function (onUpdate, onError)
{
// store user callbacks
this.onUpdate = onUpdate;
this.onError = onError;
// setup internal event handlers
this.onSongEnd = onSongEnd.bind (this);
// allocate an Ajax handler
try
{
this.ajax = window.XMLHttpRequest
? new XMLHttpRequest()
: new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e)
{
// fatal error: could not get an Ajax handler
this.onError ("could not allocated Ajax handler");
}
this.ajax.onreadystatechange = onAjaxUpdate.bind(this);
// launch initial request
//ADDED CODE
onSongEndWrapper();
//END ADDED CODE
this.onSongEnd ();
// ------------------------------------------
// interface
// ------------------------------------------
// try another refresh in the specified amount of seconds
this.retry = function (delay)
{
setTimeout (this.onSongEnd, delay*5000);
}
// ------------------------------------------
// ancillary functions
// ------------------------------------------
// called when it's time to refresh the playlist
function onSongEnd ()
{
this.ajax.open('GET', 'playlist.php',
true);
this.ajax.send(null);
}
//ADDED CODE
function onSongEndWrapper()
{
alert("extra function added");
this.onSongEnd();
}
//END ADDED CODE
// handle Ajax request progress
function onAjaxUpdate ()
{
if (this.ajax.readyState != 4) return;
if (this.ajax.status == 200)
{
// get our response
var list = eval ('('+this.ajax.responseText+')');
// compute milliseconds remaining till the end of the current song
var start = new Date(list.dbdata[0].date_played.replace(' ', 'T')).getTime();
var now = (list.servertime);
var d = start - now + 6500
+ parseInt(list.dbdata[0].duration);
if (d < 0)
{
// no new song started, retry in 3 seconds
d = 3000;
}
else
{
// notify caller
this.onUpdate (list);
}
// schedule next refresh
//ADDED CODE
setTimeout (onSongEndWrapper.bind(this), d);
//END ADDED CODE
}
else
{
// Ajax request failed. Most likely a fatal error
this.onError ("Request failed");
}
}
}
var list = new PlayList (playlistupdate, playlisterror);
function playlistupdate (list)
{
for (var i = 0 ; i != list.dbdata.length ; i++)
{
var song = list.dbdata[i];
}
{
$("#list0artist").html(list.dbdata[0].artist);
$("#list0title").html(list.dbdata[0].title);
}
}
function playlisterror (msg)
{
// display error message
console.log ("Ajax error: "+msg);
// may want to retry, but chances of success are slim
list.retry (10); // retry in 10 seconds
}
创建包装函数。
setTimeout (onSongEndWrapper.bind(this), d);
function onSongEndWrapper()
{
alert("extra function added");
this.onSongEnd();
}
要开始onload添加
document.body.addEventListener("load", startPlayList, false);
function startPlayList()
{
list = new PlayList (playlistupdate, playlisterror);
}
并更改此:
var list = eval ('('+this.ajax.responseText+')');
至:
var list = JSON.parse(this.ajax.responseText);
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.