Javascript 装载和执行

<script language="javascript" type="text/javascript">
    function cachejs(script_filename){
        var cache = document.createElement(‘object‘);
        cache.data = script_filename;
        cache.id = "coolshell_script_cache_id";
        cache.width = 0;
        cache.height = 0;
        document.body.appendChild(cache);
    }
 
    function loadjs(script_filename) {
        var script = document.createElement(‘script‘);
        script.setAttribute(‘type‘, ‘text/javascript‘);
        script.setAttribute(‘src‘, script_filename);
        script.setAttribute(‘id‘, ‘coolshell_script_id‘);
 
        script_id = document.getElementById(‘coolshell_script_id‘);
        if(script_id){
            document.getElementsByTagName(‘head‘)[0].removeChild(script_id);
        }
        document.getElementsByTagName(‘head‘)[0].appendChild(script);
    }
 
    function LoadJS(){
        var script = ‘./alert.js‘;
        loadjs(script);
    }
 
</script>
 
 
...
 
<p style="cursor: pointer" onclick="LoadJS()">Click to load alert.js </p>
 
...
...
<script>
    cachejs(‘./alert.js‘);
</script>