执行远程或内敛javascript，支持script中包含document.write。用于将js广告渲染到target, 基于tangram

executeScript.js

/**
 * 执行远程或内敛javascript，支持script中包含document.write
 * 用于将js广告改为渲染到target, 基于tangram
 *
 * executeScript({
 *     'target': baidu.g('ad'),
 *     'url': 'http://ecma.bdimg.com/adtest/0116fb68cf061c3ec55516d4c79946ca.js'
 * });
 *
 * executeScript({
 *     'target': baidu.g('ad'),
 *     'text': 'alert("alert");document.open();document.write('open');document.close();'
 * });
 *
 * @param {Object} scriptOpt options.
 * @param {Element|string} scriptOpt.target target节点.
 * @param {string} scriptOpt.url javascript脚本的链接地址.
 * @param {string} scriptOpt.text 内敛javascript脚本.
 * @param {function} scriptOpt.callback 远程javascript脚本执行后的回调函数.
 * @param {string=} scriptOpt.opt_type script dom和生成的html的插入位置
 *                                     默认为inside，还有before和after
 */
executeScript = function (scriptOpt) {
    var target = baidu.g(scriptOpt['target']);
    var insertType = scriptOpt['opt_type'] || 'inside';
    var scriptUrl = scriptOpt['url'];
    var inlineScript = scriptOpt['text'];
    var doc = target.ownerDocument;
    var oldWrite = doc.write;
    var writeMethodName = {
        'inside': 'beforeEnd',
        'before': 'beforeBegin',
        'after': 'afterEnd'
    };
    // 重设document.write
    doc.write = function (txt) {
        // TODO
        // 如果write的输入中包含document.write就无法执行了
        baidu.dom.insertHTML(target, writeMethodName[insertType], txt);
    };
    var callback = function () {
        // 恢复document.write;
        doc.write = oldWrite;
        if (scriptOpt['callback']) {
            scriptOpt['callback']();
        }
    };

    if (scriptUrl) {
        // remote script
        var script = document.createElement('script');
        var readyStates = {
            'complete': 1,
            'loaded': 1,
            'undefined': 1 // for non-ie
        };
        script.src = scriptUrl;
        var insertScriptNode = {
            'inside': function (script) {
                target.appendChild(script);
            },
            'before': function (script) {
                baidu.dom.insertBefore(script, target);
            },
            'after': function (script) {
                baidu.dom.insertAfter(script, target);
            }
        };
        script.onload = script.onerror = script.onreadystatechange =
            function() {
                if (readyStates[script.readyState]) {
                    callback();

                    script.onload = script.onerror = script.onreadystatechange = null;
                    try {
                        if (script.clearAttributes) {
                            script.clearAttributes();
                        }
                        else {
                            for (var p in script) {
                                delete script[p];
                            }
                        }
                    }
                    catch (x) {}
                    script = null;
                }
            };
        insertScriptNode[insertType](script);
    }
    else if (inlineScript) {
        // 获取target所在环境的window对象的eval
        (doc.defaultView || doc.parentWindow).eval(inlineScript);
        callback();
    }
};