Question

1）为什么在IE 8中 typeof（window [“alert”]）是“对象”而不是功能？
2）如何在“window.alert”上调用apply方法？我的意思是我要做的就是：

function exec(method, param)
{
    //because of typeof(window["alert"]) == "object" the actual if looks like typeof(window[method]) == 'function' || method == 'alert'
    if(typeof(window[method]) == 'function')
    {
        window[method].apply(window, [param]);
    }
}

exec("alert","hello");

Answer 1

typeof window ['alert']是一个“功能”......（用FF测试）

尝试此代码（typeof而不是typeOf（））

function exec(method, param)
{
    if(typeof window[method] == 'function')
    {
        window[method].apply(window, [param]);
    }
}

exec("alert","hello");

Answer 2

typeof window["alert"]在9以下的Internet Explorer版本中返回“object”，但在Firefox中它返回“function”。我想这是一个众所周知的问题。下面是一篇提到它的文章：

https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/typeof?redirectlocale=en-US&redirectslug=Core_JavaScript_1.5_Reference%2FOperators%2FSpecial_Operators%2Ftypeof_Operator

Answer 3

typeof（window [“alert”]）返回“function”

您已撰写 typeOf 。这工作

function exec(method, param)
{
    //because of typeof(window["alert"]) == "object" the actual if looks like typeof(window[method]) == 'function' || method == 'alert'
    if(typeof(window[method]) == 'function')
    {
        window[method].apply(window, [param]);
    }
}

exec("alert","hello");

JavaScript typeof，alert和apply

3 个答案: