如何强制小书签只运行一次？

发布于 2024-12-03 19:50:34 字数 670 浏览 0 评论 0原文

我的小书签包含对插入到 body 中的“启动器”脚本的调用。当它运行时，它会以类似的方式插入更多脚本（jQuery，实际应用程序）和 CSS。

Bookmarklet

javascript:(function(){
    var l = document.createElement('script');
    l.setAttribute('type','text/javascript');
    l.setAttribute('src','launcher.js');
    document.body.appendChild(l);
})();

Launcher.js

var s = document.createElement('script');
s.setAttribute('type','text/javascript');
s.setAttribute('src','my actual script');
document.body.appendChild(s);

// I repeat a block like this once per script/css.

问题是，如果单击该书签两次，所有脚本都将再次插入。我怎样才能防止这种行为？

原文

My bookmarklet consist of a call to a 'launcher' script that is inserted into body. As it runs, it inserts in a similar way more scripts (jQuery, the actual application), and a CSS.

Bookmarklet

javascript:(function(){
    var l = document.createElement('script');
    l.setAttribute('type','text/javascript');
    l.setAttribute('src','launcher.js');
    document.body.appendChild(l);
})();

Launcher.js

var s = document.createElement('script');
s.setAttribute('type','text/javascript');
s.setAttribute('src','my actual script');
document.body.appendChild(s);

// I repeat a block like this once per script/css.

The problem is that if the bookmarklet is clicked twice, all the scripts will be inserted again. How can I prevent this behavior?

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放赐 2024-12-10 19:50:34

您可以在 window 对象上设置一个属性，该属性的名称很奇怪，因此仅在第一次运行时不太可能导致命名空间冲突。在后续运行中，如果该属性存在，则代码将不会执行：

    javascript:(function(){
      // Test for existence of your weird property
      if (!window.hasOwnProperty('yourWeirdPropertyX774x9ZZYy4')) {

          // Run all your existing code
          var l = document.createElement('script');
          l.setAttribute('type','text/javascript');
          l.setAttribute('src','launcher.js');
          document.body.appendChild(l);

         // Set the flag so this won't run again
         window.yourWeirdPropertyX774x9ZZYy4 = true;
      }  
    })();

You can set a property on the window object which is oddly named, so it is unlikely to cause namespace collisions, on the first run only. On subsequent runs, the code will not execute if the property is present:

    javascript:(function(){
      // Test for existence of your weird property
      if (!window.hasOwnProperty('yourWeirdPropertyX774x9ZZYy4')) {

          // Run all your existing code
          var l = document.createElement('script');
          l.setAttribute('type','text/javascript');
          l.setAttribute('src','launcher.js');
          document.body.appendChild(l);

         // Set the flag so this won't run again
         window.yourWeirdPropertyX774x9ZZYy4 = true;
      }  
    })();

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白色秋天 2024-12-10 19:50:34

我发现执行此操作的最简洁方法是命名加载外部 js 文件的函数，该函数与我希望每次用户单击小书签时运行的外部文件内的函数同名。这样，当第一次单击小书签时，它会加载外部文件，并在随后单击时运行外部文件中的函数。

这是一些 sudo 代码：

这将是 bookmarklet 链接的 url 中的代码

if( ! bookmarklet){
    var bookmarklet = {
     click: function(){
         js = document.createElement('SCRIPT');
         js.type = 'text/javascript';
         js.src = 'http://external.js?' + (Math.random());
         document.getElementsByTagName('head')[0].appendChild(js);
     }
   };
}
bookmarklet.click(); // this will be called everytime the bookmarklet is clicked

external.js 文件将包含一个具有相同名称的函数，如下所示：

var bookmarklet = {
    click:function(){
         // insert logic you want to run every time the bookmarklet is clicked
    }
};
bookmarket.click(); // run once after file is loaded

这样，当加载外部文件时您的函数（示例函数是 bookmarklet.js） click）现在在外部加载的文件中运行该函数，并且不会再次加载外部js文件。

I found the cleanest way for me to do this was to name the function that loads the external js file, the same name as a function inside the external file that I want to be ran everytime the user clicks the bookmarklet. This way when the bookmarklet is clicked the first time, it loads the external file and on subsquent clicks a function in the external file is ran.

Here is some sudo code:

This would be the code in the url of the bookmarklet link

if( ! bookmarklet){
    var bookmarklet = {
     click: function(){
         js = document.createElement('SCRIPT');
         js.type = 'text/javascript';
         js.src = 'http://external.js?' + (Math.random());
         document.getElementsByTagName('head')[0].appendChild(js);
     }
   };
}
bookmarklet.click(); // this will be called everytime the bookmarklet is clicked

The external.js file would contain a function with the same name like this:

var bookmarklet = {
    click:function(){
         // insert logic you want to run every time the bookmarklet is clicked
    }
};
bookmarket.click(); // run once after file is loaded

This way when the external file is loaded your function (example function is bookmarklet.click) now runs the function inside the externally loaded file and will not load the external js file a second time.

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