Created
September 6, 2012 15:41
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限制单实例运行
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| <!DOCTYPE HTML> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title></title> | |
| <script src="./test.js" type="text/javascript"></script> | |
| </head> | |
| <body> | |
| <span id="test"></span> | |
| </body> | |
| </html> |
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| /* | |
| * http://www.douban.com/people/2790109/status/1004046271/ | |
| * 一个应用多个实例间只允许一个实例运行 | |
| * localStorage.clear()的时候会出问题，没有做恢复~ | |
| * runner其实不需要每次都检查localStorage.runningId | |
| */ | |
| window.onload = function(){ | |
| // if localStorage.clear(), all will be stoped, | |
| // create a new page will restart | |
| testEl = document.getElementById('test'); | |
| var CHECK_TIME = 500; | |
| var TIMEOUT_TIME = 1000; | |
| var myId; | |
| var runningId = parseInt(localStorage.runningId, 10); | |
| var lastRunnerId = parseInt(localStorage.lastId, 10); | |
| //id init | |
| if(runningId && lastRunnerId){ | |
| myId = lastRunnerId + 1; | |
| } | |
| else { | |
| myId = 1; | |
| localStorage.runningId = myId; | |
| } | |
| localStorage.lastId = myId; | |
| localStorage.timeStamp = localStorage.timeStamp || Date.now(); | |
| setInterval(function(){ | |
| //check id | |
| var runningId = parseInt(localStorage.runningId, 10); | |
| if (runningId === myId){ | |
| // i'm running | |
| localStorage.timeStamp = Date.now(); | |
| run(); | |
| } | |
| else { | |
| // i'm waiting | |
| if(Date.now() - localStorage.timeStamp > TIMEOUT_TIME){ | |
| // check timeout, be the runner | |
| localStorage.timeStamp = Date.now(); | |
| localStorage.runningId = myId; | |
| } | |
| else{ | |
| // still waiting | |
| wait(); | |
| } | |
| } | |
| }, CHECK_TIME); | |
| }; | |
| function run(){ | |
| var msg = 'i\'m runnging'; | |
| testEl.innerText = msg; | |
| console.log(msg); | |
| }; | |
| function wait(){ | |
| var msg = localStorage.runningId + ' is running~'; | |
| testEl.innerTest = msg; | |
| console.log(msg); | |
| }; |
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