捕获块不捕获错误

Question

I have this code and when I manipulate the try block so that there occur errors the catch block does not catch them (for example errors that the Facebook SDK throws). I am really new to using the try and catch structure and do not understand how I can handle the facebook errors.

try{

    window.fbAsyncInit = function() {
        FB.init({
          appId      : 'XXXXXXXXXXXX',
          xfbml      : true,
          version    : 'v2.7'
        });
        FB.AppEvents.logPageView();

    };

  (function(d, s, id){
     var js, fjs = d.getElementsByTagName(s)[0];
     if (d.getElementById(id)) {return;}
     js = d.createElement(s); js.id = id;
     js.src = $fbSource;  
     fjs.parentNode.insertBefore(js, fjs);
   }(document, 'script', 'facebook-jssdk'));

}catch(e){

    console.log('Error: '+e);

}

Answer 1

That's because the errors aren't being thrown when the try block is active. By the time the errors are being thrown (later, when Facebook calls your fbAsyncInit function), the code has long since exited the try block.

If you want to catch those errors, you'll need a try block within your fbAsyncInit callback and/or to receive errors in the way the FB API indicates, since most async APIs can't (by nature) be compatible with try/catch .