如何覆盖console.log

Question

I am using the following code to override the console.log function, because I want to print console.log only if showConsole returns true .

var proxyConsolelog = window.console.log;


console.log=function(msg){
    try{
        if(Boolean(showConsole))
        {
            proxyConsolelog(msg);
        }
    }catch(e){
        alert(JSON.stringify(e.message));
        proxyConsolelog('ERROR-->>'+e.message);
    }
}

The proxyConsolelog line creates a problem, and alert(JSON.stringify(e.message)); is giving me a "Type error".

And I get this:

void SendDelegateMessage(NSInvocation *): delegate (webView:runJavaScriptAlertPanelWithMessage:initiatedByFrame:) failed to return after waiting 10 seconds. main run loop mode: kCFRunLoopDefaultMode

in the log.

How can I achieve this?

Answer 1

The problem you have is that the receiver ( this ) when you call your function, isn't the console.

You can do this :

var proxyConsolelog = window.console.log.bind(window.console);

If you need to be compatible with IE8 (which doesn't have bind ), you may do this :

var logFun = window.console.log;
var proxyConsolelog = function(){
     logFun.apply(window.console, arguments)
};

As you tagged the question jquery , then you may also use proxy :

var proxyConsolelog = $.proxy(window.console.log, window.console);

Once you have your new function, you can call it just like console.log :

proxyConsolelog('some', {arg:'uments'});