Sencha touch 中的一段源码匿名中定义Function并调用

/* 
 
This file is part of Sencha Touch 2 
 
Copyright (c) 2012 Sencha Inc 
 
Contact:  http://www.sencha.com/contact 
 
Commercial Usage 
Licensees holding valid commercial licenses may use this file in accordance with the Commercial Software License Agreement provided with the Software or, alternatively, in accordance with the terms contained in a written agreement between you and Sencha. 
 
If you are unsure which license is appropriate for your use, please contact the sales department at http://www.sencha.com/contact. 
 
*/  
(function() {  
    function write(content) {  
        document.write(content);  
    }  
  
    function meta(name, content) {  
        write('<meta name="' + name + '" content="' + content + '">');  
    }  
  
    var xhr = new XMLHttpRequest();  
    xhr.open('GET', 'app.json', false);  
    xhr.send(null);  
  
    var options = eval("(" + xhr.responseText + ")"),  
        scripts = options.js || [],  
        styleSheets = options.css || [],  
        i, ln, path;  
  
    meta('viewport', 'width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no');  
    meta('apple-mobile-web-app-capable', 'yes');  
    meta('apple-touch-fullscreen', 'yes');  
  
    for (i = 0,ln = styleSheets.length; i < ln; i++) {  
        path = styleSheets[i];  
  
        if (typeof path != 'string') {  
            path = path.path;  
        }  
  
        write('<link rel="stylesheet" href="'+path+'">');  
    }  
  
    for (i = 0,ln = scripts.length; i < ln; i++) {  
        path = scripts[i];  
  
        if (typeof path != 'string') {  
            path = path.path;  
        }  
  
        write('<script src="'+path+'"></'+'script>');  
    }  
  
})();